Bulletin  59 
T  P         DEPARTMENT  OF  THE  INTERIOR 


BUREAU     OF     MINES 

JOSEPH  A.  HOLMES,  DIRECTOR 


INVESTIGATIONS  OF 


DETONATORS  AND  ELECTRIC  DETONATORS 


IC-NRLF 


CLARENCE  HALL 

AND 

SPENCER  P.  HOWELL 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1913 


Bulletin  59 

DEPARTMENT  OF  THE  INTERIOR 
BUREAU     OF     MINES 

JOSEPH  A.  HOLMES,  DIRECTOR 


INVESTIGATIONS  OF 
DETONATORS  AND  ELECTRIC  DETONATORS 


BY 

CLARENCE  HALL 

AND 

SPENCER  P.  HOWELL 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1913 


First  edition.     June,  1913. 


\   \ 


CONTENTS. 


Page. 

Introduction 5 

Preliminary  considerations 7 

Theory  of  detonation 9 

Detonation  of  high  explosives 10 

Electric  detonators  tested 11 

Explosives  used  in  the  tests 12 

Tests  previously  used  to  determine  strength  of  detonators  and  electric  detonators .  14 

Tests  for  determining  directly  the  strength  of  P.  T.  S.  S.  electric  detonators. . .  18 

Character  of  electric  detonators  tested 18 

Squirted  lead  block  tests 20 

Cast  lead  block  tests 21 

Tests  by  explosion  of  detonating  fuse  (Cordeau  detonant)  by  influence 22 

Tests  by  depression  of  lead  plates 24 

The  nail  test 25 

Tests  for  determining  indirectly  the  strength  of  P.  T.  S.  S.  electric  detonators. .  27 

Rate-of-detonation  tests 27 

Tests  with  an  explosive  of  class  1,  subclass  a 27 

Tests  with  an  explosive  of  class  1,  subclass  b 29 

Tests  with  a  20  per  cent  "  straight"  nitroglycerin  dynamite 31 

Tests  with  a  40  per  cent  strength  ammonia  dynamite  containing  nitro- 

substitution  compounds 32 

Tests  with  a  40  per  cent  strength  ammonia  dynamite 33 

Tests  with  a  35  per  cent  strength  gelatin  dynamite  2  years  old 33 

Tests  with  a  40  per  cent  strength  gelatin  dynamite,  frozen 35 

Tests  with  a  35  per  cent  strength  gelatin  dynamite  3  years  old 35 

Small  lead  block  tests 36 

Tests  with  a  20  per   cent   "straight"  nitroglycerin  dynamite  with  6 

per  cent  of  added  water 36 

Tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite,  frozen 

and  containing  less  than  6  per  cent  of  added  water '.  37 

Tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite,  frozen 

and  containing  6  per  cent  of  added  water 37 

Tests  with  a  40  per  cent  strength  ammonia  dynamite  with  6  per  cent 

of  added  water 38 

Tests  with  a  40  per  cent  strength  gelatin  dynamite,  frozen 39 

Explosion-by-influence  tests 40 

Tests  with  an  explosive  of  class  1,  subclass  a 41 

Tests  with  an  explosive  of  class  4 41 

Tests  with  a  40  per  cent  strength  •  ammonia  dynamite  containing 

nitrosubstitution  compounds 43 

Tests  with  a  35  per  cent  strength  gelatin  dynamite  2  years  old 43 

Percentages  of  detonations  in  indirect  tests  of  P.  T.  S.  S.  electric  detonators .  44 

Comparative  explosive  efficiency 44 

Comparative  explosive  efficiency  of  P.  T.  S.  S.  electric  detonators 46 

Tests  of  four  No.  6  electric  detonators  of  different  makes 46 

Physical  examination 47 

Weight  and  composition  of  charges 47 

Results  of  calorimeter  tests 49 

Squirted  lead  block  tests 49 

Cast  lead  block  tests 50 

Tests  with  lead  plates 50 

Detonators  on  end 50 

Detonators  on  side '•- 51 

M185882 


4  CONTENTS. 

Tests  of  four  No.  6  electric  detonators  of  different  makes — Continued. 

Nail  tests 

Rate-of-detonation  tests 

Tests  with  an  explosive  of  class  1,  subclass  a 

Tests  with  an  explosive  of  class  1,  subclass  b 

Tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite 

Tests  with  a  40  per  cent  strength  ammonia  dynamite  containing  nitro- 

substitution  compounds 

Tests  with  a  35  per  cent  strength  gelatin  dynamite  2  years  old 

Tests  with  a  40  per  cent  strength  gelatin  dynamite,  frozen 

Tests  with  a  35  per  cent  strength  gelatin  dynamite  3  years  old 

Small  lead  block  tests 

Tests  with  a  20  per  cent  "straight'*  nitroglycerin  dynamite 

Tests  with  a  40  per  cent  strength  ammonia  dynamite 

Tests  with  a  40  per  cent  strength  gelatin  dynamite,  frozen 57 

Explosion-by-influence  tests 58 

Tests  with  an  explosive  of  class  1,  subclass  a. .' 58 

Tests  with  an  explosive  of  class  4 58 

Tests  with  a  40  per  cent  strength  ammonia  dynamite  containing 

nitrosubstitution  compounds 59 

Tests  with  a  35  per  cent  strength  gelatin  dynamite  2  years  old 60 

Trauzl  lead  block  tests 61 

Percentages  of  detonations  in  indirect  tests  of  four  kinds  of  No.  6  electric 

detonators 

Comparative  explosive  efficiency 

Comparative  explosive  efficiency  of  four  kinds  of  No.  6  electric  detonators. . 

Relative  strength  of  detonators  and  electric  detonators 

Tests  with  a  trinitrotoluene  detonating  fuse 

Tests  with  detonators  distributed  in  charge 

Use  of  two  kinds  of  explosives  in  the  same  drill  hole 

Publications  on  mine  accidents  and  tests  of  explosives 


ILLUSTRATIONS. 


PLATE     I.  Results  of  cast  lead  block  tests  of  P.  T.  S.  S.  electric  detonators  . . . 

II.  Scoring  of  lead  plates  by  P.  T.  S.  S.  electric  detonators  Nos.  3, 4,  5,  6, 

7,  and  8  laid  on  end 

III.  Scoring  of  lead  blocks  by  P.  T.  S.  S.  electric  detonators  Nos.  3,4,5,  6, 
7,  and  8  laid  on  side 

IV.  A,  Results  of  nail  tests  of  P.  T.  S.  S.  electric  detonators  Nos.  3,4,5,  6, 
7,  and  8;  B,  Results  of  nail  tests  of  No.  6  electric  detonators 

V.  A,  Results  of  small  lead  block  tests  of  P.  T.  S.  S.  electric  detonators 
Nos.  3,  4,  5,  6,  7,  and  8;  B,  Results  of  small  lead  block  tests  of  No.  6 
electric  detonators;  C,  Scoring  of  lead  plates  by  four  No.  6  electric 

detonators  laid  on  side 

VI.  Results  of  cast  lead  block  tests  of  four  No.  6  electric  detonators 

VII .  Scoring  of  lead  plates  by  four  No.  6  electric  detonators  placed  on  end . 
FIGURE  1.  Cross-sectional  view  of  six  P.  T.  S.  S.  electric, detonators 

2.  Nail  in  position  for  test  of  electric  detonator 

3.  Comparative  explosive  efficiency  of  six  grades  of  P.  T.  S.  S.  electric 

detonators  as  determined  by  indirect  tests 46 

A.  Cross-sectional  view  of  four  No.  6  electric  detonators  of  different 

makes 47 

5.  Comparative  explosive  efficiency  of  four  kinds  of  No.  6  electric 

detonators  as  established  by  indirect  tests 64 


INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC 

DETONATORS. 


By  CLARENCE  HALL  and  SPENCER  P.  Ho  WELL. 


INTRODUCTION. 

Among  the  more  important  factors  involved  in  the  use  of  high 
explosives  in  blasting  operations  is  the  means  employed  to  bring  about 
the  detonation  of  the  charge.  When  flame  is  applied  to  high  explo- 
sives many  of  them  may  burn  if  not  confined;  but  all  of  them  when 
burning  under  certain  conditions  of  confinement  may  detonate. 
Detonation  may  also  be  effected  by  mechanical  means,  such  as  fric- 
tional  impact  caused  by  a  blow  or  by  rubbing  between  surfaces.  By 
this  means,  however,  the  full  effect  of  the  explosive  charge  may  not 
be  developed,,  so  that  a  partial  detonation,  often  accompanied  by  the 
burning  of  the  explosive,  results. 

When  nitroglycerin  was  first  used  it  was  fired  by  the  application  of 
flame,  but  considerable  difficulty  was  experienced  in  exploding  it  with 
certainty  and  in  ob tabling  uniform  results.  In  1864  Alfred  Noble,  a 
Swedish  engineer,  discovered  that  nitroglycerin  could  be  surely  and 
completely  detonated  by  exploding  in  contact  with  it  a  small  quantity 
of  an  initiatory  explosive.  Mercury  fulminate  was  the  substance 
then  found  capable  of  producing  the  best  results  There  are  many 
other  fulminates  and  other  substances  that  will  produce  complete 
detonation  of  commercial "  high  "  explosives,  but  detonators  or  electric 
detonators  containing  mercury  fulminate  as  the  characteristic  ingre- 
dient are  still  almost  exclusively  used  in  this  country. 

The  term  " detonator"  is  used  in  the  publications  of  the  Bureau  of 
Mines  to  designate  what  the  miner  calls  a  "blasting  cap'7 — a  copper 
capsule  containing  a  small  quantity  of  some  detonating  compound 
that  is  ignited  by  a  fuse.  The  term  "  electric  detonator"  is  applied  to 
a  blasting  cap  that  is  similar  except  for  being  ignited  by  means  of  a 
small  wire  which  is  heated  to  incandescence  or  fused  by  the  passage 
of  an  electric  current. 

One  of  the  conditions  prescribed  by  the  Bureau  of  Mines  for  a  per- 
missible explosive  a  is  that  it  shall  be  fired  by  a  detonator,  or  prefer- 
ably an  electric  detonator,  having  a  charge  equivalent  to  that  of  the 
standard  detonator  used  at  the  Pittsburgh  testing  station.  A  further 

a  Permissible  explosives  have  a  short,  quick  flame  and  are  intended  especially  for  use  in  coal  mines 
containing  inflammable  gases  or  dusts.    (See  Miners'  Circular  6,  Bureau  of  Mines.) 

5 


6  *'  :  INV^&T3X£\ilbNS  OF  DETONATORS  AND  ELECTRIC   DETONATORS. 


:tK$b  ^this  charge  shall  consist  by  weight  of  90  parts  of 
mercury  fulminate  and  10  parts  of  potassium  chlorate  (or  their  equiv- 
alents). 

At  the  request  of  a  manufacturer  of  permissible  explosives,  an  inves- 
tigation was  undertaken  by  the  bureau  to  determine  the  relative 
strength  of  detonators  and  electric  detonators  having  different  com- 
positions. The  tests  of  electric  detonators  herein  reported  were 
conducted  by  H.  F.  Braddock,  junior  chemist;  J.  W.  Koster,  J.  E. 
Tiffany,  junior  mining  engineers;  and  A.  S.  Crossfield,  junior  explo- 
sives chemist,  at  the  Pittsburgh  testing  station  of  the  bureau.  Similar 
tests  of  detonators  were  not  conducted  because  it  was  believed  that  the 
results  would  not  show  sufficient  variation  to  warrant  such  tests.  It 
is  hoped  that  the  conclusions  drawn  from  the  tests  made  will  be  of 
service  to  those  using  explosives  by  enabling  them  to  select  the 
grade  of  detonator  or  electric  detonator  that  will  insure  the  most 
effective  results.  The  conclusions  are  given  in  this  bulletin,  which  is 
published  by  the  Bureau  of  Mines  as  one  of  a  series  of  publications 
dealing  with  the  testing  of  explosives  and  the  precautions  that  should 
be  taken  to  increase  safety  and  efficiency  in  the  use  of  explosives 
in  mining  operations. 

The  results  of  the  experiments  described  in  this  bulletin  show  that 
the  average  percentage  of  failures  of  explosives  to  detonate  was  in- 
creased more  than  20  per  cent  when  the  lower  grades  of  electric 
detonators  were  used  instead  of  No.  6  electric  detonators,  and  was 
increased  more  than  50  per  cent  when  these  lower  grades  were  used 
instead  of  No.  8  electric  detonators.  It  is  noteworthy,  however, 
that  when  sensitive  explosives,  such  as  40  per  cent  strength  ammonia 
dynamite  (p.  33),  were  tested  under  conditions  ideal  for  detonation,  the 
same  energy  was  developed  irrespective  of  the  electric  detonator  used. 
When  tests  were  made  with  a  less  sensitive  explosive,  such  as  a  40 
per  cent  strength  ammonia  dynamite  containing  nitrosubstitution 
compounds  (p.  32),  the  energy  developed  increased  with  the  grade  of 
the  electric  detonator  used.  For  example,  the  average  efficiency  of 
four  different  explosives  was  increased  10.4  per  cent  when  a  No.  6 
electric  detonator  was  used  instead  of  a  No.  4  electric  detonator,  and 
14.9  per  cent  when  a  No.  8  electric  detonator  was  used  (see  tabulation 
on  p.  45).  The  results  of  the  tests  emphasize  the  importance  of  using 
explosives  in  a  fresh  condition,  but  as  fresh  explosives  can  not  always 
be  had  in  mining  work,  strong  detonators  should  be  used  in  order  to 
offset  any  deterioration  of  explosives  from  age. 

The  results  obtained  substantiate  the  following  conclusions:  (1) 
That  for  any  particular  manufacturer's  detonators  or  electric  deto- 
nators the  explosive  efficiency  increases  with  their  grade,  and  (2) 
that  the  four  No.  6  electric  detonators,  of  different  makes,  tested  have 
practically  the  same  explosive  efficiency  as,  and  each  is  considered 
equivalent  to,  the  Pittsburgh  testing  station  standard  No.  6  electric 


PELIMINARY    CONSIDERATIONS.  7 

detonator  for  use  with  permissible  explosives  in  coal  mines  when  the 
No.  6  grade  is  prescribed. 

PRELIMINARY  CONSIDERATIONS. 

Methods  for  determining  the  strength  of  detonators  or  electric  deto- 
nators by  mechanical  effects  may  be  classed  as  either  direct  or  indi- 
rect. The  direct  method  comprises  those  tests  in  which  the  mechan- 
ical effect  of  the  detonators  or  electric  detonators  is  determined.  The 
indirect  method  comprises  those  tests  in  which  the  mechanical  effect 
of  the  explosives  with  which  the  detonators  or  electric  detonators  are 
used  is  determined.  The  direct  method  offers  the  advantage  of  sim- 
plicity, and  usually  of  cheapness,  but  may  lead  to  grave  inaccuracies 
unless  checked  by  mechanical  effects  indirectly  determined.  The 
discussion  under  the  heading,  "  Tests  Previously  Used  to  Determine 
the  Strength  of  Detonators"  illustrates  this. 

The  indirect  method  of  determining  the  mechanical  effects  of  ex- 
plosives, or  the  energy  developed  by  them,  approximates  practical 
conditions  and  offers  an  accurate  means  for  determining  the  relative 
efficiency  of  detonators  and  electric  detonators  in  bringing  about 
complete  detonation  of  commercial  uhigh"  explosives. 

As  all  direct  methods  of  testing  detonators  are  therefore  dependent 
on  the  indirect  method  for  verification,  the  first  experiments  under- 
taken were  to  determine  the  relative  strength  of  electric  detonators 
indirectly  by  comparing  the  energy  developed  by  different  commercial 
explosives  when  fired  with  different  grades  of  electric  detonators. 
Afterwards  tests  were  made  by  determining  the  relative  strength  of 
electric  detonators  by  direct  means,  and  a  test  was  devised  that, 
although  not  entirely  satisfactory,  gave  results  that  approximated 
more  closely  those  established  by  the  indirect  tests. 

Detonating  explosives  develop  their  energy  in  the  most  efficient 
way  when  fired  with  detonators  or  electric  detonators  that  completely 
detonate  or  explode  them.  Obviously,  if  the  detonation  be  incom- 
plete, a  part  of  the  potential  energy  of  the  explosive  will  not  be 
released,  and  the  loss  of  energy  will  be  proportional  to  the  percentage 
of  the  charge  that  did  not  detonate.  In  blasting  operations  an  incom- 
plete detonation  is  not  only  a  menace  to  safety,  by  reason  of  the  pos- 
sible explosion  of  the  unexploded  part  of  the  charge  and  of  the  harm- 
ful gaseous  products  resulting  from  the  blast,  but  in  many  cases  it 
acts  like  an  underloaded  shot  and  performs  little,  if  any,  useful  work. 

If  an  explosive  is  in  a  fresh  condition  and  is  sensitive  to  detonation 
and  no  obstacles  are  present  to  hinder  its  detonation,  then  any  deto- 
nator effective  enough  to  cause  its  complete  detonation  will  develop 
its  full  energy. 

In  practice,  however,  conditions  ideal  for  detonation  rarely  and 
perhaps  never  exist,  because  the  commercial  explosives  are  somewhat 
insensitive  to  detonation  or  because  they  may  have  deteriorated  by 


8          INVESTIGATIONS  OF   DETONATORS  AND  ELECTRIC   DETONATORS. 

aging  before  use.  Furthermore,  crimped  paper  ends  of  the  cartridges, 
loose  material  in  the  drill  hole,  air  spaces  between  the  cartridges,  or 
cartridges  of  too  small  diameter  may  hinder  detonation. 

An  explosive  is  said  to  age  when  any  physical  or  chemical  change 
during  storage  affects  its  sensitiveness,  its  uniformity,  or  its  stability. 
Such  changes  are  usually  caused  by  the  temperature  and  the  humidity 
of  the  air  or  by  sunlight,  and  even  gravity  may  have  an  important 
effect.  If  the  explosive  is  placed  in  the  sunlight,  it  may  become 
unstable.  If  a  cartridge  of  dynamite  is  subjected  to  a  temperature 
above  90°  F.,  gravity  may  cause  the  segregation  of  nitroglycerin  in 
the  lower  end  or  side  of  the  cartridge.  If  nitroglycerin  explosives  are 
subjected  to  temperatures  alternately  above  and  below  52°  F.,  the 
nitroglycerin  tends  to  segregate  in  the  cartridge.  These  conditions 
affect  the  uniformity  of  the  explosives.  If  explosives,  especially 
those  containing  ammonium  nitrate  or  other  hygroscopic  salts,  are 
subjected  to  a  moist  atmosphere  they  tend  to  absorb  moisture.  If 
the  temperature  is  less  than  52°  F.,  nitroglycerin  explosives  other  than 
low-freezing  ones  may  freeze,  and  low-freezing  explosives  will  freeze 
at  a  temperature  less  than  35°  F.  Recently,  there  have  been  placed 
on  the  market  nitroglycerin  explosives,  styled  nonfreezing  explosives, 
that  are  declared  by  the  manufacturers  to  remain  unfrozen  when  the 
temperature  falls  as  low  as  0°  F.  Both  moisture  and  freezing  affect 
the  sensitiveness  of  explosives. 

The  results  of  preliminary  tests  indicated  that  it  would  be  impos- 
sible to  discriminate  between  commercial  electric  detonators  by  deter- 
mining the  energy  developed  by  explosives  used  with  them  unless  the 
explosives  were  insensitive  to  detonation  or  tested  under  conditions 
which  would  simulate  their  use  under  actual  mining  conditions;  con- 
sequently the  authors,  in  testing  electric  detonators  indirectly,  used 
explosives  in  an  insensitive  condition.  This  was  done  by  using  those 
that  were  naturally  insensitive,  such  as  an  explosive  of  class  1,°  sub- 
class b;  by  using  explosives  in  cartridges  having  small  diameters,  such 
as  the  20  per  cent  " straight"  nitroglycerin  dynamite  in  cartridges  of 
J-inch  diameter;  in  an  aged  condition,  such  as  the  35  per  cent  strength 
gelatin  dynamite  two  years  old ;  in  a  frozen  condition,  such  as  40  per 
cent  strength  gelatin  dynamite ;  and,  in  the  case  of  ammonia  dynamite, 
by  the  addition  of  water. 

The  apparatus  used  in  the  experimental  study  were  the  Mettegang 
recorder,  small  lead  blocks,  and  Trauzl  lead  blocks.  The  results  of 
the  tests  differentiated  the  electric  detonators  in  two  ways.  In  the 
first  place  the  electric  detonator  either  did  or  did  not  cause  the  deto- 
nation of  the  explosives.  In  tabulating  such  results  the  number  of 
detonations  is  expressed  as  the  percentage  of  the  number  of  trials. 
Only  the  tests  of  those  explosives  were  considered  in  which  at  least 
one  failure  to  detonate  occurred  and  in  which  detonation  occurred  in 

a  For  an  explanation  of  classification  see  p.  12. 


THEORY   OF   DETONATION.  9 

at  least  one  trial.  In  the  second  place,  those  trials  in  which  detona- 
tion occurred  were  used  as  a  basis  of  comparing  the  relative  explosive 
efficiency  of  the  electric  detonators.  The  results  of  only  those  tests 
in  which  each  of  the  electric  detonators  of  the  series  caused  detonation 
were  recorded.  The  results  are  expressed  in  percentages  of  explosive 
efficiency  as  compared  with  the  Pittsburgh  testing  station  standard 
No.  6  electric  detonator.  This  electric  detonator  offered  the  advan- 
tage of  being  included  in  both  groups  tested — the  Pittsburgh  testing 
station  standard  and  the  four  No.  6  electric  detonators. 

THEORY  OF  DETONATION. 

A  short  discussion  of  the  theory  of  detonation  as  presented  by 
Berthelota  is  necessary  in  order  that  a  better  interpretation  of  the 
experiments  herein  reported  can  be  made.  The  theory  is  called  the 
u  explosive-wave  "  theory,  and  it  has  been  generally  accepted  because 
all  detonation  phenomena  can  be  best  explained  by  it.  In  order  to 
analyze  the  propagation  of  an  explosive  wave,  the  wave  is  considered 
as  a  recurring  cycle  of  released  and  transformed  energy  with  four 
phases,  as  follows:  Mechanical  to  calorific,  calorific  to  chemical  (the 
phase  in  which  the  potential  energy  of  the  explosive  material  is 
released),  chemical  to  calorific,  and  calorific  to  mechanical. 

This  cycle  can  best  be  readily  understood  by  indicating  how  the  explo- 
sive wave  is  propagated  through  a  cylindrical  file  of  a  homogeneous 
explosive  without  the  loss  of  enough  energy  to  interrupt  propagation. 

1 .  Transformation  of  mechanical  energy  to  calorific  energy. — When 
an  explosive  detonates  a  part  of  the  mechanical  energy  of  a  layer  of  the 
explosive  is  converted  instantly  into  heat  energy  in  the  adjacent 
layer  by  reason  of  the  impact  of  molecules.     The  efficiency  of  this 
conversion  is  low — certainly  less  than  50  per  cent — as  the  movement 
of  the  molecules  is  radial  and  they  are  only  partly  confined  by  the 
layer  of  explosive  in  the  file.     The  mechanical  energy  that  is  not 
converted  into  heat  energy  exerts  pressure  on  the  confining  medium 
and  thus  becomes  the  vehicle  through  which  work  is  accomplished. 
There  is  good  reason  for  believing  that  the  thickness  of  the  layer  of 
explosive  that  enters  into  the  first  phase  of  the  cycle  varies  with  the 
physical  properties  of  the  explosive  material,  principally  with  its 
elasticity  and  partly  with  the  velocity  of  the  molecules  that  are  in 
molecular  vibration.     The  less  elastic  the  explosive  material  and 
the  greater  the  velocity  of  the  molecules  the  thinner  the  layer,  and 
hence  the  more  times  the  cycle  will  recur  in  a  unit  length  of  the 
explosive  material. 

2.  Transformation  of  calorific  energy  to  chemical  energy. — Some  of 
the  calorific  energy  of  the  layer  is  used  to  overcome  the  chemical 
stability  of  the  explosive  material,  which  may  vary  widely,  and  thus 
release  the  potential  energy  of  the  layer;  the  rest  of  the  calorific 

a  Berthelot,  M.,  Explosives  and  their  power,  1892,  pp.  88-113. 


10   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 

energy  is  used  to  accelerate  and  reinforce  the  chemical  action.  The 
layer  of  explosive  by  this  time  is  developing  a  tremendous  Mnetic 
energy  as  expressed  in  phase  3. 

3.  Transformation  of  chemical  energy  to  calorific  energy. — All  com- 
mercial explosives  develop  heat  on  detonation.     This  phase  is  different 
from  the  others  because  each  of  those  represents  some  kind  of  kinetic 
energy  derived  entirely  from  the  preceding  phase,  and  consequently 
no  one  of  them  can  have  more  kinetic  energy  than  the  preceding 
phase  is  capable  of  transferring.     The  conversion  in  this  phase  is 
complete  because  all  the  potential  energy  released  becomes  kinetic 
energy,  which  is  largely  calorific  energy. 

4.  Transformation    of  calorific   energy   to   mechanical   energy. — A 
simple  statement  of  this  phase  is  that  the  larger  volume  of  gases  then 
formed  from  the  layer  of  explosives  is  in  an  extremely  active  state 
of  molecular  vibration  and  that  these  molecules  are  then  manifesting 
their  energy  as  mechanical  energy.     The  efficiency  of  conversion  of 
calorific  energy  to  mechanical  energy  is  high  because  the  conversion 
is  very  rapid  and  radiation  and  conduction  losses  are  correspondingly 

small. 

DETONATION  OF  HIGH  EXPLOSIVES. 

All  methods  used  to  initiate  the  explosive  wave,  or  to  detonate 
high  explosives,  involve  the  application  of  heat.  If  heat  be  applied 
directly  by  means  of  a  flame  such  as  is  produced  by  a  fuse,  squib,  or 
electric  igniter,  or  by  a  spark  or  an  incandescent  solid,  and  the 
explosive  be  of  the  first  order,  or  directly  explosive,  such  as  mercury 
fulminate  or  iodide  of  nitrogen,  then  detonation  is  sure  and  effective. 
If,  however,  the  explosive  be  of  the  second  order,  or  indirectly  explo- 
sive, such  as  dynamite,  permissible  explosives,  trinitrotoluene,  or 
guncotton,  then  detonation,  especially  complete  detonation,  does  not 
usually  occur;  hence  the  direct  application  of  heat  is  not  a  sure  and 
effective  means  of  producing  detonation. 

If  heat,  such  as  is  produced  by  the  physical  resistance  of  the  explo- 
sive to  a  blow  or  impact,  be  applied  indirectly  to  high  explosives, 
then  any  sufficient  blow  or  impact  will  cause  detonation;  that  is,  it 
will  initiate  the  four-phase  energy  cycle,  or  explosive  wave. 

Because  the  impact  produced  by  detonators  is  extremely  quick, 
and  their  mercury-fulminate  composition  has  a  high  density  and 
releases  considerable  kinetic  energy,  the  force  of  the  impact  is  in- 
stantly converted  into  heat  which  is  applied  to  a  thin  layer  of 
the  explosive  material,  thereby  overcoming  the  chemical  stability 
of  that  layer  and  initiating  the  explosive  wave.  Experience  and 
investigation  has  proved  this  means  of  producing  the  detonation 
of  explosives,  those  not  too  insensitive,  to  be  both  sure  and  effective ; 
hence  one  is  not  surprised  to  learn  that  detonators  are  universally  used. 

As  the  mercury-fulminate  composition  of  detonators  is  an  explo- 
sive of  the  first  order  it  may  be  detonated  by  fire,  and  hence  fuse  may 


ELECTRIC  DETONATORS  TESTED.  11 

be  used  in  connection  with  them.  Fuse  is  made  of  a  uniform  out- 
side diameter  and  detonators  are  made  of  a  uniform  inside  diameter 
such  that  the  fuse  fits  snugly  into  them.  In  using  fuse,  it  is  cut 
square  across  and  inserted  into  the  detonator  until  it  gently  touches 
the  fulminate  mixture  and  then  the  detonator  is  crimped  on  the  fuse. 
Similarly  a  detonator  may  be  fired  by  means  of  a  small  platinum 
wire  embedded  into  the  priming  composition  and  brought  to  incan- 
descence or  fused  by  the  passage  of  an  electric  current.  (See  figs.  1 
and  4.)  The  priming  composition  may  be  simply  an  easily  inflamed 
material  such  as  loose  guncotton,  a  match  composition,  an  explosive 
of  the  first  order  such  as  mercury  fulminate,  or  a  mercury-fulminate 
composition.  The  priming  composition  is  placed  in  the  detonator 
directly  above  and  in  contact  with  the  main  charge.  The  platinum 
bridge  is  attached  at  each  end  to  an  insulated  wire;  the  two  wires, 
called  the  legs,  pass  through  the  plug  and  the  filling,  and  are  con- 
nected by  leading  wires  to  the  source  of  the  electric  current.  When 
a  detonator  is  fitted  with  means  of  firing  by  an  electric  current  it  is 
called  an  electric  detonator.  Electric  detonators  are  particularly 
adapted  to  shot  firing  in  fiery  mines,  or  to  the  simultaneous  firing 
of  several  charges.  They  are  also  adapted  to  any  purpose  for  which 
detonators  may  be  used,  and  as  their  use  offers  a  greater  assurance 
of  safety  they  are  growing  in  favor. 

ELECTRIC  DETONATORS  TESTED. 

The  electric  detonators  tested  were  designated  as  the  Pittsburgh 
testing  station  standard  No.  3,  No.  4,  No.  5,  No.  6,  No.  7,  and  No.  8, 
the  Western  Coast  No.  6,  the  special  No.  6,  and  the  foreign  No.  6. 
For  brevity  the  expression  Pittsburgh  testing  station  standard  is 
abbreviated  in  this  paper  to  P.  T.  S.  S. 

The  P.  T.  S.  S.  No.  3  electric  detonators  were  made  at  the  testing 
station  from  No.  3  detonators.  A  cross-sectional  view  of  one  of 
these  electric  detonators  is  shown  in  figure  1.  The  priming  charge 
consisted  of  0.02  gram  of  dry,  loose  guncotton  directly  above  and  in 
contact  with  the  compressed  charge.  The  sulphur  plug,  the  insulated- 
wire  legs,  and  the  platinum  bridge  were  so  placed  that  the  bridge  was 
embedded  in  the  loose  guncotton.  Then  the  molten  sulphur  was 
poured  over  the  plug  until  the  cap  was  filled. 

As  detonators  in  this  country  are  made  of  a  uniform  inside  diam- 
eter of  0.220  inch  and  electric  detonators  of  a  uniform  inside  diameter 
of  0.260  inch,  the  P.  T.  S.  S.  No.  3  electric  detonators  are  smaller  in 
diameter  than  all  the  others  except  the  special  No.  6  electric  detonators 
which  were  also  assembled  at  the  Pittsburgh  testing  station.  It  was 
impossible  to  procure  No.  3  electric  detonators  in  the  open  market, 
as  their  manufacture  has  recently  been  discontinued. 

The  priming  charge  used  in  the  No.  3,  the  No.  5,  and  the  No.  7 
electric  detonators  consisted  of  loose  guncotton;  that  in  the  No.  4, 


12   INVESTIGATIONS  OF  DETONATOES  AND  ELECTRIC  DETONATORS. 

the  No.  6,  and  the  No.  8  electric  detonators  was  commercially  pure 
mercury  fulminate. 

The  Western  Coast  No.  6  and  the  foreign  No.  6  electric  detonators 
were  used  as  received.  The  special  No.  6  electric  detonator  was 
made  at  the  testing  station  in  the  same  manner  as  the  P.  T.  S.  S. 
No.  3.  The  primer  of  the  western  coast  No.  6  was  loose  guncotton; 
that  of  the  foreign  No.  6  was  a  mixture  of  picric  acid  and  chlorate  of 
potash.  The  foreign  No.  6  was  so  called  because  the  detonator  was 
imported,  but  the  priming  charge,  sulphur  plug,  and  wires  were 
assembled  by  a  manufacturer  in  this  country. 

These  electric  detonators  are  representative  of  all  the  electric 
detonators  commercially  used  in  the  United  States. 

The  P.  T.  S.  S.  No.  4,  No.  5,  No.  6,  No.  7,  and  No.  8  were  used  as 
received  from  the  manufacturers.  Because  of  the  seemingly  erratic 
results  of  tests  with  the  P.  T.  S.  S.  No.  5  electric  detonators,  attention 
is  called  to  the  fact  that  they  were  from  3  to  3J  years  old  when  used, 
and  that  although  the  sulphur  plug  protected  the  fulminating  com- 
position somewhat,  they  were  not  in  first-class  condition. 

EXPLOSIVES  USED  IN  THE  TESTS. 

The  explosives  used  in  the  tests  are  enumerated  below;  they  in- 
cluded certain  permissible  explosives  and  different  grades  of  commer- 
cial dynamites.  Explosives  designated  as  permissible  by  the  bureau 
are  grouped  in  four  classes.®  Class  1,  ammonium-nitrate  explosives, 
includes  all  explosives  in  which  the  characterisitc  material  is  ammo- 
nium nitrate.  The  class  is  divided  into  two  subclasses:  Subclass  a, 
including  every  ammonium-nitrate  explosive  that  contains  a  sensi- 
tizer  that  is  itself  an  explosive,  and  subclass  6,  including  every 
ammonium-nitrate  explosive  that  contains  a  sensitizer  that  is  not  in 
itself  an  explosive.  Class  2,  hydrated  explosives,  includes  all  explo- 
sives in  which  salts  containing  water  of  crystallization  are  the  char- 
acteristic materials.  Class  3,  organic-nitrate  explosives,  includes  all 
explosives  in  which  the  characteristic  material  is  an  organic  nitrate 
other  than  nitroglycerin.  Class  4,  nitroglycerin  explosives,  includes 
all  explosives  in  which  the  characteristic  material  is  nitroglycerin. 

The  permissible  explosives  used  in  the  tests  were  as  follows:  Sam- 
ple 1,  sample  2,  and  sample  3  of  an  explosive  of  class  1,  subclass  a; 
sample  1  and  sample  2  of  an  explosive  of  class  1,  subclass  6;  and  an 
explosive  of  class  4. 

The  commercial  grades  of  dynamites  used  were  a  20  per  cent 
"straight"  nitroglycerin  dynamite;  a  40  per  cent  strength  ammonia 
dynamite  (containing  nitrosubstitution  compounds);  a  40  per  cent 
strength  ammonia  dynamite;  a  35  per  cent  strength  gelatin  dynamite 
(2  years  old);  a  35  per  cent  strength  gelatin  dynamite  (3  years 
old);  and  a  40  per  cent  strength  gelatin  dynamite. 

a  See  Miners'  Circular  6,  Bureau  of  Mines,  1912,  p.  16, 


EXPLOSIVES  USED  IN   TESTS. 


13 


The   results    of   physical    examination    of    the    above-mentioned 
explosives  were  as  follows: 

Results  of  physical  examination  of  explosives  used  in  tests. 


Class  and  grade  of 
explosives. 

1  Diameter  of  car- 
tridge. 

i 

°& 

a 

5*» 

M 

g 

jA 

3f 

£ 

Cartridges  re- 
dipped. 

O  £ 

181 

£* 

if 

Color. 

Consistence. 

Class  1,  subclass  a  (sam- 
ple 1). 
Class  1  subclass  a  (sam- 

In. 

li 

li 

In. 

8 

g 

Gms. 
160 

174 

No.. 
Yes 

1.01 
1.09 

Corn  
do 

Granular  and  fibrous;  fine;  soft; 
dry;  slightly  cohesive. 
Do. 

pie  2). 
Class  1,  subclass  a  (sam- 
ple 3). 
Class  1  ,  subclass  6  (sam- 
ple 1). 
Class  1,  subclass  6  (sam- 
ple 2). 
Class  4 

li 

H 
U 
ij 

8 

8 
8 
g 

227 
277 
278 
166 

Yes. 
Yes. 
Yes. 
No 

.93 

.88 
.88 
1.00 

Mauve  
Corn  
do  
do  

Powdered;  very  fine;  soft;  dry;  not 
cohesive. 
Powdered;  very  fine;  very  dry; 
very  soft;  not  cohesive. 
Do. 

Granular  and  fibrous;   soft;   fine; 

20  per  cent  "straight" 

i 

g 

103 

No 

i  is 

do 

drv;  slightly  cohesive. 
Do, 

nitroglycerin     dyna- 
mite. 
40  per  cent  strength  am- 
monia dynamite  (con- 
taining nitrosubstitu- 
tion  compounds). 

H 

71 

g 

226 
241 

Yes. 
Yes 

1.34 
1  43 

do  
Drab  

Fibrous;     very  fine;    dry;    soft; 
slightly  cohesive. 

Granular;  fine;  dry;  soft;  slightly 

monia  dynamite. 
35  per  cent  strength  gel- 
atin   dynamite  (2 
years  old). 

If 

13 

7i 

71 

265 
339 

No.. 

No 

1.63 
1  66 

Corn  
...  do.  . 

cohesive. 
Gelatinous;  fine;  wet;  soft;  mod- 
erately cohesive. 

Do. 

atin   dynamite  (3 
years  old). 
40  per  cent  strength  gel- 
atin dynamite. 

U 

7J 

295 

No.. 

1.60 

Drab  

Do. 

Certain  of  the  different  explosives  used  in  the  tests  were  analyzed, 
with  results  as  follows: 

Results  of  analyses  of  certain  explosives  used  in  tests. 


Kind  qf  explosives. 

L£ 

e§3 

A 

AS 

an 

^ 

•fe  Q 

jd^^'0' 

Q.ti  SoTS 

S0 
|| 

ar 

1 

Constituent. 

0 

a 

§i* 

|| 

i- 

G^K       | 

|| 

|-of 

•gt»2 

!§ 

I-  C?8 

o.j2  fi  w 

gi 

g     ° 

8*°  ^ 

«.s 

jtgj 

sjfj 

fts 

«  a  oj 

r 

8fla 

s 

508 

^5 

%*** 

§ 

Moisture  .  . 

1  20 

1  93 

0.88 

1.89 

5.86 

1.47 

Nitroglycerin  

19.54 

16.28 

21.60 

29.03 

28.10 

30.70 

Nitrololuene... 

4.97 

Nitrocellulose 

.88 

1.17 

.88 

Sodium  nitrate  

c62  09 

47.14 

46.04 

48.62 

52.20 

54.27 

Ammonium  nitrate 

18  78 

18.86 

Wood  pulp 

15.22 

5.45 

5.55 

8.58 

Wood  pulp  and  crude  fiber 

2.84 

2.15 

Calcium  carbonate 

1  95 

1.44 

1.13 

Zinc  oxide  

.62 

.88 

1.07 

1.02 

Sulphur.  .  . 

2  84 

4.85 

4.83 

4.58 

3.08 

Starch 

3  79 

11.47 

Vaseline  

.81 

Paraffin  

1.24 

Rosin 

.23 

Total  . 

100.00 

100.00 

100.00 

100.00 

100.00 

100.00 

Analyst,  W.  C.  Cope.         &  Analyst,  A.  L.  Hyde,         c  Contains  1.04  per  cent  sodium  chloride. 


14        INVESTIGATIONS  OF   DETONATORS  AND  ELECTRIC   DETONATORS. 


TESTS   PREVIOUSLY   USED    TO    DETERMINE    STRENGTH 
OF    DETONATORS    AND    ELECTRIC    DETONATORS. 

Six  principal  tests  have  been  used  previously  to  determine  the 
strength  of  detonators  or  electric  detonators.  They  are  as  follows: 

1.  Weight  of  charge. — Ever  since  it  was  observed  that  certain  ex- 
plosives would  not  always  detonate  with  a  certain  weight  of  charge 
of  mercury  fulminate  or  mercury-fulminate  composition  and  that 
these  same  explosives  would  always  detonate  if  the  weight  of  charge 
hi  the  detonator  was  increased,  it  has  been  customary  to  vary  the 
charge  in  the  detonators  and  to  consider  the  weight  of  the  charge  to 
be  an  indication  of  the  strength  of  the  detonator.  There  are  several 
grades  of  detonators,  and  they  are  designated  by  the  charge  of  ful- 
minate composition  contained  in  them. 

Bigg-Wither a  arranged  the  following  table,  which  was  published 
in  1900: 

Weight  of  charge  in  different  grades  of  detonators. 


Charge  per  detonator. 

Grams. 

Grains. 

1 

0.30 

4.6 

2 

.40 

6.2 

3 

.54 

8.3 

4 

.65 

10.0 

5 

.80 

12.3 

6 

1.00 

15.4 

6* 

1.25 

19.2 

7 

1.50 

23.1 

8 

2.00 

30.9 

It  is  to  be  noted  that  in  1900  there  was  no  great  variation  in  the 
composition  of  detonators.  There  is  no  indication  that  the  rela- 
tion between  the  effectiveness  of  the  detonator  and  the  weight  of  the 
charge  was  other  than  directly  as  the  first-power  function. 

2.  Deformation  or  penetration   of  lead  or  iron  plates. b — Guttman* 
states:  "One  of  the  oldest  and  most  frequently  used  tests  for  meas- 
uring the  power  of  caps  (used  only  with  ordnance)  consisted  of  ex- 
ploding them  on  a  lead  or  iron  plate  resting  on  a  hollow  iron  ring  and 
estimating  their  strength  from  the  deformation  or  the  penetration 
of  the  block.     For  larger  detonators  of  between  one-half  gram  and  1 
gram  charge  as  used  for  borehole  shots,  the  plate  would  have  to  be 
of  greater  thickness." 

3.  Radial  lines  on  lead  plates. — Bigg- Wither,  hi  the  article  men- 
tioned above,  describes  in  considerable  detail  tests  made  with  differ- 
ent detonators.     He  used  lead  plates  3  mm.  thick  for  detonators 
Nos.  1  to  3  and  lead  plates  5  mm.  thick  for  detonators  Nos.  4  to  8. 

o  Bigg-Wither,  H.,  Notes  on  detonators:  Trans.  Inst.  Min.  Eng.,  vol.  21, 1900,  p.  442. 
&  Munroe,  C.  E.,  Lecture  on  chemistry  and  explosives,  1888,  pp.  22-23. 
c  Guttman,  Oscar,  Manufacture  of  explosives,  vol.  2, 1895,  p.  369. 


TESTS   PREVIOUSLY   USED. 


15 


The  lead  plates  were  supported  on  the  edges,  and  the  detonators  were 
placed  vertically  on  the  centers  of  the  plates.  He  further  states  that 
after  the  tests  the  plates  may  be  taken  as  direct  pictorial  records 
of  the  efficiency  of  the  detonators  but  that  they  do  not  record  the 
report  of  the  explosion,  the  recording  of  which  is  essential;  that  the 
detonating  effect  is  not  shown  so  much  by  the  punctures  as  by  the 
fine  radiating  marks  upon  the  surface  of  the  plates;  that  the  fine 
markings  show  that  the  force  of  the  explosion  smashes  the  copper 
tubing  to  powder,  some  of  which  often  adheres  to  the  sides  of  the 
plates,  and  that  when  there  are  fine  radiating  lines  around  the  cen- 
ter there  are  heavier  markings  outside.  The  difference  in  effect  is 
probably  due  to  the  upper  part  of  the  fulminate  not  being  com- 
pletely detonated.  The  results  of  tests  show  that  detonators  may 
absorb  moisture  when  stored  and  emphasize  the  importance  of 
using  a  detonator  of  higher  power  than  would  be  otherwise  actually 
requisite. 

It  appears,  then,  that  this  test  is  one  that  might  readily  be  used  to 
distinguish  between  good  and  poor  or  defective  detonators  regardless 
of  the  charge  that  they  contain,  and  for  this  purpose  the  test  appears 
to  have  considerable  merit.  However,  as  an  indication  of  the  rela- 
tive effectiveness  of  detonators  of  different  grades,  that  is,  contain- 
ing different  weights  of  charge,  it  appears  to  have  little  value. 

4.  Photographs  of  fashes  from  electric  detonators. — De  Grave a  con- 
ceived the  idea  that  the  flash  or  flame  of  a  detonator  might  vary  with 
the  grade  of  the  detonator,  and  such  was  the  result  of  tests  made  by 
him.  He  also  showed  that  there  was  little,  if  any,  difference  whether 
the  electric  detonator  was  of  high  or  low  tension.  The  following 
table  gives  the  results  for  low- tension  detonators: 

Results  of  photographs  of  flashes  of  low-tension  detonators. 


Grade 
No.— 

Dimension  of 
flash. 

Inches. 

3 

1.0  by  0.22 

6 

1.6   by   .22 

7 
7 

1.76  by   .22 
1.76  by   .22 

8 

2.0   by    .22 

8 

2.0   by    .22 

This  test  was  rather  unique,  but  from  the  results  of  tests  reported 
it  is  evident  that  this  test  offers  no  advantage  over  that  of  the  simple 
determination  of  the  weight  of  charge  contained  within  the  detonator. 

5.  Ability  of  detonator  to  explode  similar  detonators. — This  test  is 
fully  stated  in  a  circular  dated  September  10,  1903,  issued  by  the 
chief  inspector  of  explosives  (Great  Britain)  to  the  manufacturers 

a  Photographs  of  flashes  of  electric  detonators:  Trans.  Inst.  Min.  Eng.,  vol.  15, 1897,  p.  203. 
78875°— Bull.  59—13 2 


16       INVESTIGATIONS  OF   DETONATORS  AND  ELECTRIC   DETONATORS. 


and  importers  of  detonators.  The  detonator  is  there  defined0  as 
"A  capsule  or  case  of  such  strength  and  construction  and  contain- 
ing one  or  the  other  of  the  following  explosives  of  the  fulminate  class 
in  such  quantities  that  the  explosion  of  one  capsule  or  case  will 
communicate  the  explosion  to  other  capsules  or  cases:  (1)  Fulminate 
of  mercury,  (2)  fulminate  of  mercury  and  chlorate  of  potash,  (3) 
other  compositions." 

It  is  obvious  from  the  definition  that  with  this  test  no  discrimina- 
tion between  the  detonators  of  different  grades  is  possible. 

6.  Effect  on  lead  Hock  when  detonator  is  fired  in  bore  hole. — At  the 
Massachusetts  Institute  of  Technology  in  1888-89,  tests  were  con- 
ducted by  Robert  C.  Williams  and  J.  B.  Seager  and  reported  by 
Frederick  W.  Clark.6 

Tests  were  made  of  20  explosives,  triple  and  quintuple  detona- 
tors (caps)  being  used.  In  order  that  some  of  the  effect  of  the  detona- 
tor itself  might  be  eliminated  its  effect  was  determined  in  the  follow- 
ing way:  The  lead  block  used  was  a  frustum  of  a  cone  5J  inches 
high,  5£  inches  in  diameter  at  the  bottom,  and  5  inches  in  diameter 
at  the  top.  The  axial  bore  was  also  a  frustum  of  a  cone  three-fourths 
of  an  inch  in  diameter  at  the  top,  five-eighths  of  an  inch  in  diameter  at 
the  bottom,  and  2£  inches  deep.  In  casting  the  blocks  the  lead  was 
poured  when  "just  barely  melted";  the  finished  block  weighed  about 
45  pounds.  The  detonator  was  placed  in  the  bore  hole,  tamped  with 
dry  quartz  sand,  and  fired  by  means  of  fuse.  As  the  detonators  were 
slightly  less  than  one-fourth  of  an  inch  in  diameter  the  distance  between 
the  caps  and  the  walls  of  the  bore  hole  averaged  three-sixteenths  of  an 
inch.  A  tabulation  of  the  results  of  the  tests  follows: 

Results  of  firing  detonators  in  bore  holes  of  lead  blocks. 


• 

Grade  of  detonator  (cap). 

Capacity  of  bore  hole. 

Difference. 

Average. 

Before 
firing 
detonator. 

After 
firing 
detonator. 

"Eagle" 
Do.. 
Do 

triples 

C.c. 
14.3 
14.3 
14.3 
14.3 
14.3 

C.c. 
17.0 
16.3 
16.6 
17.2 
17.5 

C.c. 
2.7 
2.0 
2.3 
2.9 
3.2 

C.c. 
2.3 

}             3.! 

"Eagle" 
Do. 

quintuple  6  

«  At  that  time  the  commercial  grade  name  of  the  Pittsburgh  testing  station  No.  3  detonator. 
6  At  that  time  the  commercial  grade  name  of  the  Pittsburgh  testing  station  No.  5  detonator. 

It  is  evident  that  the  method  of  conducting  these  tests  was  such 
that  only  a  part  of  the  energy  of  the  detonator  was  represented  by 
the  expansion  of  the  bore  hole  because  much  of  the  energy  was 

o  Practical  Coal  Mining,  vol.  2, 1903,  p.  237. 

ft  Some  tests  of  the  relative  strength  of  nitroglycerin  and  other  explosives:  Trans.  Am.  Inst.  Min.  Eng., 
VOl.  18, 1890,  p.  515. 


TESTS   PREVIOUSLY   USED. 


17 


used  to  disintegrate  and  pulverize  the  sand.  This  was  proven  by 
tests  made  at  the  Pittsburgh  testing  station  with  electric  detonators 
containing  similar  charges.  A  No.  3  electric  detonator  when  fired 
in  a  cast-lead  block  with  a  bore  hole  of  such  size  that  the  detonator 
would  fit  snugly  within  it  produced  an  expansion  of  5.8  c.  c.  A 
similar  test  with  a  No.  5  electric  detonator  gave  an  expansion  of 
9.2  c.  c. 

In  the  tests  at  the  Massachusetts  Institute  of  Technology,  two  deto- 
nators fired  simultaneously  within  the  bore  hole  produced  consid- 
erably more  than  twice  the  expansion  produced  by  one  detonator, 
probably  because  the  distance  between  the  charge  and  the  sides  of 
the  bore  hole  was  less  and,  accordingly,  the  charging  density  was 
increased.  The  following  tabulated  results  show  this: 

Results  of  firing  simultaneously  two  detonators  in  bore  hole  of  lead  block. 


Grade  of  detonator  (cap). 

Capacity  of  bore  hole- 

Difference. 

Average. 

Before 
firing 
detonator. 

After 
firing 
detonator. 

"Eagle"  triple            

C.c. 
14.3 
14.3 
14.3 

C.c. 
21.9 
20.4 
20.0 

C.c. 
7.6 
6,1 

9.7 

C.c. 
}               6.8 
9.7 

Do 

"Eagle"  quintuple  

Further  lead-block  tests  were  made  with  13  sensitive  explosives, 
both  triple  and  quintuple  detonators  (caps)  being  used.  The  charge 
consisted  of  6  grams  of  explosive,  loaded  and  fired  as  previously 
described.  The  conclusion  drawn  was  that  explosives  when  fired 
with  a  quintuple  detonator  produce  9.7  per  cent  greater  expansion 
than  that  produced  with  a  triple  detonator. 

It  is  evident  that  in  arriving  at  this  conclusion  the  author  did 
not  take  into  consideration  the  fact  that  the  quintuple  detonator 
had  a  charge  of  0.80  gram  of  fulminating  composition,  that  the 
triple  detonator  had  only  a  0.54-gram  charge,  and  that  therefore  the 
weight  of  the  total  charge,  including  the  quintuple  detonator,  was 
increased  4.0  per  cent  over  the  weight  of  the  total  charge  when  triple 
detonators  were  used.  Furthermore,  the  4.0  per  cent  increase  in 
weight  represented  principally  mercury  fulminate,  a  powerful, 
quick-acting  explosive  which,  under  the  conditions  of  the  tests, 
would  exert  its  full  effect  in  enlarging  the  bore  hole.  From  the 
data  presented,  the  results  can  not  be  properly  interpreted  as  indi- 
cating that,  with  small  charges  (in  this  case  6  grams)  of  an  explo- 
sive detonating  directly  under  the  influence  of  a  detonator,  an 
increase  of  the  force  of  the  explosive  was  obtained  with  a  detonator 
of  the  higher  grade. 


18   INVESTIGATIONS  OF  DETONATOKS  AND  ELECTRIC  DETONATORS. 


The  results  of  tests  made  at  the  Pittsburgh  testing  station  with 
sensitive  explosives  do  not  substantiate  the  conclusions  drawn.  In 
order  to  differentiate  between  grades  of  electric  detonators,  it  was 
necessary  to  use  large  quantities  of  insensitive  explosives  under 
conditions  simulating  those  of  actual  blasting  operations. 

TESTS   FOR  DETERMINING   DIRECTLY    THE    STRENGTH 
OF  P.   T.    S.    S.   ELECTRIC   DETONATORS. 

CHARACTER  OF  ELECTRIC  DETONATORS  TESTED. 

Tests  for  determining  directly  the  strength  of  electric  detonators 
were  made  with  six  grades  of  P.  T.  S.  S.  electric  detonators  (fig.  1). 


No.  3 


No.  4 


0     .1     .2     .3    .4     .5 


No.  5 


No.  6 


SCALE  IN  INCHES. 
1 


No.  7 


No.  8 


LEGEND 

|||;|||Asphaltic  composition.  fegrglSl  Loose  gun  cotton. 

E&Pfol  Loose  mercury  fulminate.          JHHI  Compressed  mercury  fulminate  composition. 
FIGURE  1.— Cross-sectional  view  of  six  P.  T.  S.  S.  electric  detonators. 

A  physical  examination  of  each  showed  the  results  tabulated  below. 
Each  measurement  represents  an  average  of  the  measurements  of  five 
electric  detonators  of  a  given  grade. 


DIRECT   TESTS  OF   P.   T.   S.   S.   ELECTRIC  DETONATORS. 


19 


Results  of  physical  examination  of  P.  T.  S.  S.  electric  detonators. 


Grade  of 
electric 
detona- 
tor. 

Length 
of  shell. 

Outside 
diameter 
f  shell. 

Inside 
diameter 
of  shell. 

Thickness 
of  shell. 

Length 
of  com- 
pressed 
charge. 

Length  of 
priming 
charge. 

Length  of 
sulphur 
plug. 

Length  of 
asphaltic 
composi- 
tion, i  f 
any. 

Length  of 
sulphur 
filling. 

No.  3... 
No.  4  
No.5  
No.  6... 

Inches. 
1.00 
1.25 
1.55 
1.55 
1.75 
2.00 

Inches. 
0.234 
.274 
.274 
.274 
.274 
.274 

Inches. 
0  220 
260 
260 
260 
260 
260 

Inches. 
0.007 
.007 
.007 
.007 
.007 
.007 

Inches. 
0.28 
.16 
.28 
.28 
.62 
.75 

Inches. 
0.37 
.24 
.37 
.27 
.38 
.20 

Inches. 
0.25 
.31 
.28 
.25 
.25 
.31 

Inches. 

Inches. 
0.10 
.16 
.62 
.25 
.50 
.24 

0.38 

.50 

No.  7  
No.  8  

.50 

Details  of  the  wiring  of  the  electric  detonators  tested  are  given 
below : 

Details  of  the  wiring  of  six  grades  of  P.  T.  S.  S.  electric  detonators. 


Distance 

Distance 

wires 

from 

Grade  of  electric  detonator. 

projected 
below 

end  of 
insulation 

sulphur 
plug. 

to  end 
of  wires. 

Inches. 

Inches. 

No  3 

0.16 

0  16 

No.  4    . 

.12 

.88 

No.5 

16 

16 

No.  6... 

.12 

.94 

No.  7 

.19 

16 

No.  8  

.12 

.75 

The  outside  diameter  and  the  thickness  of  the  shells  were  deter- 
mined with  micrometers.  The  inside  diameter  of  the  shells  was 
computed  from  the  figures  so  determined.  For  grades  Nos.  3,  5,  and 
7  the  priming  charge  was  guncotton.  No.  3  electric  detonators 
could  not  be  procured  from  the  manufacturers,  so  the  priming  charge, 
sulphur  plug,  and  sulphur  filling  were  placed  in  a  No.  3  detonator  at 
the  Pittsburgh  testing  station;  all  other  electric  detonators  were 
purchased  from  manufacturers. 

The  weights  and  the  results  of  chemical  analyses  of  the  charges  of 
the  six  grades  of  electric  detonators  were  as  follows : 

Weigttts  and  results  of  chemical  analyses  of  charges  of  P.  T.  S.  S.  electric  detonators. 


Grade  of  electric 
detonator. 

Weight 
of  com- 
pressed 
charge. 

Weight 
of 
priming 
charge. 

Weight 
of  total 
charge. 

Percentage  in 
compressed 
charge  of  — 

Percentage  in 
priming 
charge  of  — 

Percentage  in  total 
charge  of  — 

Mer- 
cury 
fulmi- 
nate. 

Chlo- 
rate of 
potash. 

Gun- 
cotton. 

Mer- 
cury 
fulmi- 
nate. 

Mer- 
cury 
fulmi- 
nate. 

Chlo- 
rate of 
potash. 

Gun- 
cotton. 

No.  3  a  

Grams. 
0.4920 
.3255 
.6990 
.6485 
1.4854 
1.5110 

Grams. 
0.0200 
.3230 
.0240 
.3510 
.0247 
.3000 

Grams. 
0.5120 
.6485 
.7230 
.9995 
1.5101 
1.8110 

Per  ct. 

87.94 
88.51 
89.13 
88.82 
88.93 
89.77 

Perct. 
12.06 
11.49 
10.87 
11.18 
11.07 
10.23 

Perct. 
100.00 

"166.66" 

Perct. 

Perct. 
84.50 
94.24 
86.17 
92.75 
87.47 
91.47 

Perct. 
11.59 
5.76 
10.51 
7.25 
10.89 
8.53 

Perct. 
3.91 

"3  ."32 

No.  4  « 

100.00 

No.5&... 

No.66  

No.  7c.... 

100.00 

100.00 

1.64 

No.Sd  

100.00 

a  Analyst,  A.  L.  Hyde. 
b  Analyst,  W.  C.  Cope. 


c  Analyst,  C.  A.  Taylor. 
d  Analyst,  J.  H.  Hunter. 


'. 


20   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 

The  results  of  calorimeter  tests  are  tabulated  below: 

Results  of  calorimeter  tests  of  six  grades  of  P.  T.  S.  S.  electric  detonators. 


Heat  evolved 

per  electric 

detonator  on 

Grade  of  electric  detonators. 

Number  of 
electric 
detonators 
used  in 
each  test. 

Number  of 
tests 
averaged. 

Heat 
evolved 
per  electric 
detonator. 

Total 
charge  per 
electric 
detonator. 

the  basis  of  a 
charge  of  77.7 
per  cent  mer- 
cury fulminate 
and  22.3  per 
cent  chlorate  of 

potash  (exact 

combust  ion),  a 

Large 

calories. 

Grams. 

Large  calories. 

No.  3                    

30 

1 

0.35 

0.  5120 

0.36 

No.  4                                         

25 

2 

.48 

.6485 

.46 

No.  5              

20 

2 

.49 

.7230 

.51 

No.  6                                             

15 

2 

.62 

.9995 

.71 

No  7 

10 

2 

1.01 

1.5101 

1.07 

No.  8                                    

10 

2 

1.14 

1.8110 

1.28 

a  Berthelot,  M.,  Explosives  and  their  power,  1892,  p.  470. 

The  tests  were  made  with  the  explosives  calorimeter a  of  the 
Pittsburgh  testing  station  and  the  rise  in  temperature  of  the  water 
surrounding  the  bomb  was  about  0.140°  C.,  an  increase  too  small 
to  insure  the  most  accurate  results.  Nevertheless,  the  results  are 
valuable  as  showing  the  potential  energy  of  the  electric  detonators 
and  that  the  potential  energy  is  approximately  a  direct  function  of 
the  total  charge.  The  last  column  is  added  to  show  how  close  the 
heat  evolved  per  electric  detonator  was  to  that  which  was  to  be 
expected  had  the  mercury-fulminate  composition  been  of  mercury 
fulminate  and  chlorate  of  potash  in  the  proportions  necessary  for 
exact  combustion. 

SQUIRTED  LEAD  BLOCK  TESTS. 

Tests  of  the  six  grades  of  electric  detonators  were  made  with 
squirted-lead  blocks.  The  blocks  were  squirted  2  inches  in  diameter 
and  were  cut  3  inches  long.  The  axial  bore  hole  was  drilled  a  depth 
equal  to  the  length  of  the  electric  detonator  to  be  tested  and  a 
diameter  such  that  the  electric  detonator  would  fit  snugly  into  it. 
The  volume  of  the  bore  hole  was  measured  with  water  before  and 
after  firing  the  shot.  The  tendency  of  the  squirted  blocks,  because 
of  their  small  diameter  (2  inches),  to  bulge  around  the  sides  makes 
a  comparison  between  the  low-grade  and  the  high-grade  electric 
detonator  more  difficult  and  makes  impossible  a  comparison  of  the 
increase  in  volume  with  the  weight  of  total  charge.  Nevertheless, 
the  volume  increases  with  the  weight  of  total  charge  as  is  to  be 
expected. 

a  Hall,  Clarence,  Snelling,  W.  O.,  and  Howell,  S.  P.,  Investigations  of  explosives  used  in  coal  mines; 
with  a  chapter  on  the  natural  gas  used  at  Pittsburgh,  by  G.  A.  Burrell,  and  an  introduction  by  C.  E. 
Munroe:  Bull.  15,  Bureau  of  Mines,  1912,  p.  109. 


DIRECT   TESTS   OF   P.   T.   S.    S.   ELECTRIC   DETONATORS. 


21 


The  results  of  the  tests  are  tabulated  below: 

Results  of  tests  P.  T.  S.  S.  electric  detonators  with  squirted-lead  blocks. 


Volume  of 

bore  hole  — 

Increase  of 

Grade  of  electric  detonator. 

Test  No. 

Before 
firing 
detonator. 

After 
firing 
detonator. 

after  firing 
electric 
detonator. 

increase  of 
volume. 

total 
charge. 

No.  3         

AA47 

C.c. 
0.9 

C.c. 
7.5 

C.c. 
6.6 

C.c. 

\                   R   A 

Qrams. 

No.  4 

AA48 
AA45 

.9 
1.35 

7.2 
11.0 

6.3 
9.6 

1             b.4 

I                       OK 

No.  5                                   

AA46 
AA20 

1.35 

1.8 

10.8 
13.3 

9.4 
11.5 

) 

.6485 

No  6 

AA27 
AA10 

1.7 
1.7 

12.6 
20.0 

11.1 

18.3 

.7230 

No  7                      > 

AA11 
AA18 

1.7 
2.1 

19.8 
38.5 

18.1 
36.4 

j-           18.2 

I                      OC    T 

.9995 

No.  8 

AA19 
a  AA16 

1.9 
2.1 

38.9 
49.7 

37.0 
47.6 

>           36.  7 

\                      A-7     R 

1.5101 

<*AA17 

2.15 

49.6 

47.45 

}            47.5 

1.8110 

o  Bottom  blown  out  of  block;  it  was  fastened  in  with  paraffin  before  volume  of  bore  hole  was  measured. 
CAST  LEAD  BLOCK  TESTS. 

Tests  of  the  six  grades  of  P.  T.  S.  S.  electric  detonators  were  made 
also  with  cast-lead  blocks.  The  blocks  were  cast  as  solid  cylinders 
100  mm.  in  diameter  and  100  mm.  high.  The  axial  bore  hole  of  each 
was  drilled  a  depth  equal  to  the  length  of  the  electric  detonator  to  be 
tested,  and  of  a  diameter  such  that  the  electric  detonator  would  fit 
snugly  into  it.  The  volume  of  the  bore  hole  was  measured  with 
water  before  and  after  the  shot.  When  more  than  two  trials  were 
made  with  any  given  electric  detonator,  the  two  trials  that  were 
within  5  per  cent  variation  were  selected  for  averaging.  A  comparison 
of  the  average  increase  of  volume  (y)  with  increase  of  the  weight  of 
total  charge  (x)  shows  that  the  relation  y=15.5  (a;  =  0.12)  is  closely 
maintained. 

Plate  I  shows  the  comparative  effects  of  the  different  electric 
detonators  on  the  cast-lead  blocks. 

The  details  of  the  cast  lead  block  tests  are  tabulated  below : 

Results  of  tests  with  cast-lead  blocks  of  P.  T.  S.  S.  electric  detonators. 


Volume  of  bore  hole- 

Increase  of 

« 

volume  as 

Grade  of  electric 
detonator. 

Test  No. 

Increase  of 
volume. 

Average 
increase  of 
volume. 

Weight  of 
total 
charge. 

compared 
with  total 
charge,  by 
formula 

Before  fir- 
ing electric 

After  fir- 
ing electric 

detonator. 

detonator. 

y=15.5 

C.c. 

C.c. 

C.c. 

C.c. 

Grams. 

No.3  

/  AA49 
\  AA50 

0.9 
.9 

6.6 
6.8 

5.7 
5.9 

j            5.8 

0.5120 

6.1 

No.4  

/  AA51 
\  AA52 

.35 
.35 

9.3 

9.1 

7.95 
7.75 

1      " 

.6485 

8.2 

No.5  

(  AA3 
\  AA39 

.7 
.7 

11.1 
10.7 

9.4 
9.0 

9.2 

.7230 

9.3 

No  6 

J  AA30 
\  AA55 

.7 
.6 

16.0 
15.2 

14.3 
13.6 

14.0 

.9995 

13.6 

No  7 

/  AA37 
\  AA44 

.9 
.9 

23.0 

22.8 

21.1 
20.9 

}           21.0 

1.5101 

21.5 

No  8 

J  AA42 
\  AA43 

2.1 
2.1 

28.6 
28.0 

26.5 
25.9 

\           26.2 

1.8110 

26.2 

22        INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC   DETONATORS. 


TESTS   BY   EXPLOSION   OF   DETONATING   FUSE    (CORDEAU   DETO- 
NANT)a  BY  INFLUENCE. 

The  usual  method  of  firing  detonating  fuse  (cordeau  detonant)  is  to 
place  a  detonator  on  the  end  of  the  fuse.  Some  detonators  will 
explode  detonating  fuse  when  not  in  direct  contact  with  it.  Hence, 
in  the  expectation  that  the  strength  of  an  electric  detonator  might  be 
determined  by  varying  the  distance  between  the  electric  detonator 
and  the  detonating  fuse,  trials  with  a  few  electric  detonators  were 
made  in  such  a  way  as  to  fix  for  each  grade  a  limiting  distance  at 
which  no  explosion  would  occur,  explosion  occurring  if  the  distance 
were  lessened  1  mm. 

The  detonating  fuse  was  arranged  in  the  four  different  ways  indi- 
cated in  the  following  tables: 

Results  of  explosion-by -influence  tests  in  which  detonating  fuse  was  placed  parallel  with 

electric  detonator. 


Grade  of  electric  detonator. 

Test  No. 

Trial. 

Separating 
distance. 

Result. 

No  6 

M243 

a 

Mm. 
20 

No  explosion 

No.  8  

M245 

b 
c 
d 
e 
f 

I 

a 

10 
5 
0 
0 
0 
0 
0 
0 

Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 

b 
c 

0 
0 

Do. 
Do. 

Results  of  explosion-by -influence  tests  in  which  side  of  detonating  fuse  touched  the  end  of 
the  electric  detonator  and  was  at  right  angles  to  it. 


Grade  of  electric  detonator. 

Test  No. 

Trial. 

Result. 

No.  6.... 

M244 

a 

No  explosion 

No  8 

M246 

b 
c 
d 
e 
a 

Do. 
Do. 
Do. 
Do. 
Do 

b 

Do. 

Results  of  explosion-by -influence  tests  in  which  detonating  fuse  and  electric  detonator  were 
placed  in  the  same  axial  line. 


Grade  of  electric  detonator. 

Test  No. 

Trial. 

distance. 

Result. 

No.  4  

M253 

a 

Mm. 
5 

Explosion 

6 

d 
e 
f 

I 
i 

i 

8 
6 
6 
6 

7 
7 
8 
8 
8 
8 

No  explosion. 
Do. 
Do. 
Explosion. 
No  explosion. 
Explosion. 
No  explosion. 
Do. 
Do. 
Do. 

o  See  p.  66. 


DIRECT   TESTS   OF   P.    T.    S.   S.   ELECTRIC   DETONATORS. 


23 


Results  of  explosion-by-influence  tests  in  which  detonating  fuse  and  electric  detonator  were 
placed  in  the  same  axial  line — Continued. 


Grade  of  electric  detonator. 

Test  No. 

Trial. 

Separating 
distance. 

Result. 

No.  6  

M251 

a 

Mm. 
3 

Explosion. 

b 

4 

Do. 

c 

5 

Do. 

d 

6 

Do. 

€ 

7 

No  explosion. 

i 

7 

Do. 

g 

7 

Do. 

\ 

7 

Explosion. 

j 

8 

Do. 

j 

9 

Do. 

k 

10 

No  explosion. 

I 

10 

Do. 

m 

10 

Do. 

n 

10 

Do. 

0 

10 

Do. 

No  8 

M247 

a 

o 

Explosion. 

b 

0 

Do. 

c 

10 

No  explosion. 

d 

5 

Do. 

e 

1 

Explosion. 

f 

3 

Do. 

I 

i 

4 

4 
5 

No  explosion. 
Explosion. 
No  explosion. 

j 

5 

Do. 

i 

5 

Do. 

I 

5 

Do. 

Results  of  explosion-by-influence  tests  in  which  detonating  fuses  were  placed  at  right  angles 
to  electric  detonators  but  at  different  distances  from  them  in  such  a  way  that  axial  line  of 
detonating  fuse  intersected  side  of  electric  detonator. 


Grade  of  electric  detonator. 

Test  No. 

Trial. 

Distance 
from  cen- 
ter line  of 
detonating 
fuse  to  end 
of  deto- 
nator. 

Separat- 
ing dis- 
tance. 

Result. 

No.  4 

M254 

a 

Mm. 
5 

Mm. 
2 

No  explosion 

b 

1 

Explosion 

c 

2 

No  explosion 

d 

2 

Do. 

e 
/ 

2 
2 

Do. 
Do. 

No.  6  .             

M252 

a 

7 

5 

Do. 

b 

4 

Do 

c 

3 

Do. 

d 

2 

Do. 

e 
f 

—  ;  

1 

o 

Do. 
Do. 

, 

I 

0 
2 

Explosion. 
No  explosion 

i 

2 
3 

Explosion. 
No  explosion. 

{ 
I 

3 
3 

Do. 
Do. 

m 

3 

Do. 

No.8  

M250 

a 

10 

0 

Explosion. 

b 

4 

Do. 

c 
d 

5 

5 

No  explosion. 
Do.» 

e 
f 
a 

5 
6 
6 

Explosion. 
No  explosion. 
Do. 

1 

i 

6 
6 

Do. 
Do 

j 

6 

Do. 

24       INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


The  above  results  are  so  much  at  variance  with  the  established  ex- 
plosive efficiency  of  detonators  (see  pp.  45  and  46)  that  this  method  of 
determining  the  strength  of  detonators  is  considered  of  little  value. 

The  tests  made  with  the  No.  4  and  the  No.  6  electric  detonators 
placed  in  the  same  axial  line  as  that  of  the  detonating  fuse  would 
indicate  that  in  actual  blasting  there  may  be  some  advantage  gained 
from  inserting  the  electric  detonator  in  the  top  of  the  primer  or 
cartridge.  Although  it  has  been  impossible  to  show  by  tests  any  loss 
in  energy  resulting  from  the  detonation  of  an  explosive  when  the 
electric  detonator  is  placed  in  the  side  of  a  primer — that  is,  having  the 
end  of  the  electric  detonator  intersect  the  axial  line  of  the  primer, 
it  is  believed  that  the  former  method  of  insertion  is  preferable.  When 
the  top  of  the  primer  is  opened  and  an  electric  detonator  is  pushed 
into  it  and  the  paper  ends  of  the  cartridge  are  gathered  together  and 
bound  with  twine,  the  electric  detonator  is  held  firmly  hi  place.  When 
this  method  is  used  there  is  less  danger  of  the  wires  becoming  short- 
circuited,  and  it  is  impossible  for  the  end  of  the  detonator  to  project 
through  the  side  of  the  cartridge,  a  position  that  would  not  only 
tend  to  reduce  its  effectiveness,  but  would  also  be  a  source  of  danger 
in  loading  and  tamping  the  drill  hole. 

TESTS  BY  DEPRESSION  OF  LEAD  PLATES. 

The  strength  of  the  electric  detonators  was  also  determined  directly 
by  tests  involving  the  depression  of  lead  plates.  The  details  of  the 
tests  are  indicated  in  the  tabulations  following: 

Results  of  depression  tests  of  electric  detonators  placed  on  end  on  %-inch  lead  plates.0 


Grade  of  electric  detonator. 

Test  No. 

Volume 
of  water 
held  in 
depression.?* 

Diameter 
of  crater. 

Depth  of 
crater. 

Height  of 
cone  on 
bottom. 

No.3... 

M-264 

C.c. 
0.35 

Mm. 
11 

Mm. 

7 

Mm. 
2 

No.  4 

M262 

.50 

13 

7 

4 

No.  5  

M157 

.40 

13 

6 

4 

No.  6 

M149 

.40 

13 

7 

3 

No.  7  

M151 

.40 

13 

6 

2 

No.  8. 

M147 

.35 

13 

7 

2 

a  See  PI.  II. 

b  The  measurement  of  volume,  which  was  determined  with  water,  was  unsatisfactory  because  of  the  action 
of  surface  tension,  and  the  results  are  accurate  only  within  50  per  cent.  No  result  obtained  agrees  even 
approximately  with  the  established  results  of  the  explosive  efficiency  of  electric  detonators  (see  p.  45). 

Results  of  depression  tests  of  electric  detonators  placed  on  side  on  %-inch  lead  plates. a 

MEASURED    WITH    WATER. 


Grade  of  electric  detonator. 

Test  No. 

Volume.^ 

Length  of 
crater. 

Width  of 
crater. 

Depth  of 
crater. 

No.3 

M265 

C.c. 

0.30 

Mm. 
10 

Mm. 
10 

Mm. 
4 

No  4  > 

M263 

.25 

15 

10 

4 

No.  5. 

M158 

.40 

15 

11 

4 

No.  6 

cMloO 

.50 

21 

13 

5 

No.  7... 

cM152 

.60 

20 

14 

5 

No.  8. 

M148 

.90 

31 

14 

6 

a  See  PL  III. 


6  See  footnote  of  preceding  table. 


c  Bottom  of  plate  slightly  raised;  not  raised  in  other  tests. 


••!¥# 


m 


DIRECT  TESTS  OP  P.  T.  S.  S.  ELECTRIC  DETONATORS.  25 

Results  of  depression  tests  of  electric  detonators  placed  on  side  on  \-inch  lead  plates — Con. 

MEASURED    WITH    SAND.a 


Grade  of  electric 

Plate 

Weight 

of  sand 

containe 
No.— 

d  in  dep 

ression 

Aver- 
age 
of  five 

Grand 

Vol- 

detonator. 

No. 

1 

2 

3 

4 

5 

meas- 
ure- 
ments. 

age. 

ume.b 

No.  3  
No.  4  
No.  5  

M302 
M303 
M304 

1 
2 
3 
1 
2 
3 
1 

Grams. 
0.129 
.191 
.226 
.379 
.327 
.415 
.361 

Grams. 
0.122 
.191 
.209 
.405 
.325 
.393 
.359 

Grams. 
0.121 
.194 
.235 
.376 
.333 
.397 
.340 

Grams. 
0.142 
.172 
.221 
.405 
.302 
.404 
.355 

Grams. 
0.146 
.197 
.229 
.365 
.312 
.386 
.381 

Grams. 
0.132 
.189 
.224 
.386 
.320 
.399 
.359 

Grams. 
0.182 
.368 

C.c. 
0.128 
.259 

No.  6 

M301 

2 
3 
1 

.382 
.361 
.574 

.380 
.365 
.565 

.393 
.377 
.620 

.379 
.355 
.620 

.390 
.366 
.590 

.385 
.365 
.594 

.370 

.261 

No.  7 

M305 

2 
3 
1 

.580 
.622 
.891 

.586 
.600 
.867 

.607 
.615 
.890 

.569 
.601 
.880 

.596 
.598 
.892 

.588 
.607 
.884 

.596 

.420 

No  8 

M306 

2 
3 

1.002 
1.114 
1.183 

.994 
1.076 
1.173 

1.034 
1.081 
1.230 

.994 
1.108 
1.150 

1.002 
1.144 
1.244 

1.005 
1.105 
1.196 

.998 

.'703 

2 
3 

1.245 
1.269 

1.237 
1.252 

1.252 
1.257 

1.272 
1.260 

1.216 
1.320 

1.244 
1.272 

1.237 

.871 

a  The  sand  was  fine  and  dry. 

b  The  volume  was  computed  from  the  grand  average  weight  by  dividing  it  by  the  specific  gravity  of  the 
sand,  which  was  1.42.  This  test  was  acceptable  because  the  volume  of  the  depression  varied  approximately 
as  the  explosive  efficiency  of  the  electric  detonator. 

THE  NAIL  TEST. 

It  was  evident  that  the  methods  previously  used  for  the  direct 
determination  of  the  relative  strength  of  detonators  were  not  satis- 
factory or  accurate.  During  the  latter  part  of  the  investigation  an 
endeavor  was  made  to  devise  a  test  that  would  give  results  approxi- 
mating those  obtained  by  the  indirect  tests. 

In  the  tests  made  with  the  four  No.  6  detonators  having  different 
compositions,  described  later,  each  electric  detonator  caused  the  same 
amount  of  energy  to  be  developed  from  both  sensitive  and  insensitive 
explosives.  However,  by  the  direct  methods  of  testing  detonators, 
one  of  the  No.  6  detonators  showed  a  much  higher  calorific  value 
than  any  of  the  others,  and  one  developed  a  much  greater  enlarge- 
ment of  the  lead  block.  Nevertheless  it  was  concluded  that  al- 
though the  temperature  developed  and  the  volume  of  gases  pro- 
duced are  functions  of  the  efficiency  of  detonators,  the  rate  of  detona- 
tion or  the  rapidity  with  which  the  gases  are  developed  is  the  prime 
factor  and  any  tests  that  emphasized  this  factor  should  be  given  con- 
sideration. 

The  test  finally  decided  upon  is  known  as  the  nail  test.  This  test 
depends  on  the  angle  formed  by  a  nail  when  a  detonator  or  electric 
detonator  is  fired  in  close  proximity  to  it.  For  simplicity  and 
cheapness  the  nail  test  commends  itself. 

Four-inch  wire  finishing  nails  (20-d.)  are  used  in  the  test.  For  the 
tests  herein  reported  the  nails  were  selected  so  that  they  were  approx- 


26   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


imately  of  the  same  length,  the  same  gage,  and  the  same  weight.  The 
bottom  of  the  electric  detonator  was  placed  If  inches  from  the  face  of 
the  head  of  the  nail  and  was  laid  parallel  to  the  nail  and  separated  from 
it  by  two  22-gage  (0.025-inch)  copper  wires  that  were  wrapped  around 
the  electric  detonator.  The  electric  detonator  was  fastened  in  posi- 
tion by  one  strand  of  a  similar  copper  wire,  which  was  wrapped  around 
it  and  the  nail  midway  between  the  ends  of  the  electric  detonator. 
The  whole  was  suspended  horizontally  in  the  air  in  such  a  manner 

that  the  nail  was  directly 
above  the  electric  detona- 
tor, which  was  then  fired. 
(Fig.  2.)  The  impact  of  the 
exploding  electric  deto- 
nator bent  the  nail  and 
projected  it  upward.  Care 
was  taken  that  the  nail 
was  not  hurled  against  any 
solid  surface  and  further 
distorted. 

Five  trials  were  made 
with  each  grade  of  electric 
detonator.  The  angle 
through  which  the  nail  was 

FIGURE  2.— Nail  in  position  for  test  of  electric  detonator. 

bent  rrom  its  normal  posi- 
tion was  measured.  The  angle  (average  of  five  trials)  was  taken  as 
a  measure  of  the  strength  of  the  electric  detonator.  The  results 
were  as  follows: 

Results  of  nail  tests  a  of  six  grades  of  P.  T.  S.  S.  electric  detonators. 


Grade  of  electric  detonator. 

Test  No. 

Angle  of  bending  resulting  from  trial  No.  — 

Average. 

1 

2 

3 

4 

5 

No.3... 

M279 
M280 
M281 
M288 
M283 
M284 

12 
12 
11 
23 
60 
68 

10 
11 
13 
24 
50 
78 

8 
14 
14 
25 
53 
76 

9 
11 
13 
24 
54 
86 

7 
16 
8 
26 
59 
98 

0 

9.2 
12.8 
11.8 
24.4 
55.2 
81.2 

No.  4 

No.  5... 

No.  6 

No.  7... 

No.  8 

a  See  PI.  IV,  A. 

The  variation  in  the  results  of  individual  trials  was  largely  due  to 
variation  in  the  individual  electric  detonators.  An  attempt  was 
made  to  get  more  uniform  results  with  annealed  nails,  but  with 
these  there  was  practically  the  same  variation  in  results.  In  such 
tests,  as  well  as  in  all  physical  tests  of  explosives,  discrepancies  result- 
ing from  unavoidable  sources  of  error  can  not  be  eliminated,  and, 
accordingly,  only  averages  should  be  considered  in  comparing  the 
practical  value  of  the  electric  detonators. 


BUREAU    OF    MINES 


BULLETIN    59       PLATE    IV 


A.     RESULTS  OF  NAIL  TESTS  OF  P.  T.  S.  S.  ELECTRIC  DETONATORS  NOS.  3,  4,  5,  6,  7,  AND 


E.     RESULTS    OF    NAIL    TESTS    OF    NO.    6    ELECTRIC    DETONATORS,     a,  WESTERN    COAST; 
b,  SPECIAL;  c,   P.  T.  S   S.;  d,  FOREIGN. 


INDIRECT   TESTS  OF   P.   T.   S.    S.   ELECTRIC   DETONATORS. 


27 


TESTS  FOR  DETERMINING  INDIRECTLY  THE  STRENGTH 
OF  P.   T.    S.    S.   ELECTRIC  DETONATORS. 

Details  of  different  forms  of  tests  made  to  determine  indirectly  the 
strength  of  P.  T.  S.  S.  electric  detonators  are  given  below. 

RATE-OF-DETONATION  TESTS.** 

The  rate  of  detonation  of  the  explosive  was  determined  by  placing 
the  cartridges  end  to  end  in  a  28-gage  (B.  &  S.)  galvanized-iron  tube  42 
inches  long,  which  was  of  slightly  larger  diameter  than  the  cartridges. 
The  paper  ends  of  each  cartridge  were  cut  off  squarely  in  order  that 
the  explosive  material  of  the  cartridges  would  be  continuous  through- 
out the  file,  which  was  a  little  more  than  1  meter  long.  Four  copper 
wires  were  inserted  through  perforations  in  the  tube  and  the  cartridge 
file  so  that  the  distance  between  adjacent  wires  made  it  possible  to 
determine  the  rate  of  detonation  through  the  first  quarter  meter, 
the  second  quarter  meter,  the  last  half  meter,  and  the  entire  meter, 
and  the  data  were  so  recorded. 

Each  wire  carried  an  electric  current  and  was  attached  to  a  Mette- 
gang  recorder  in  such  a  way  that  at  the  instant  the  wire  was  broken 
a  spark  was  recorded  on  a  rapidly  moving  soot-covered  drum.  From 
the  sparks  thus  recorded  and  the  speed  of  the  drum,  the  time  interval 
between  the  breaking  of  the  wires  in  the  meter  file  was  computed 
and  was  expressed  as  rate  of  detonation  in  meters  per  second. 

The  rate-of-detonation  tests  were  carried  on  with  different  explo- 
sives as  described  below. 

TESTS    WITH   AN    EXPLOSIVE   OF   CLASS    1,    SUBCLASS   a. 

In  one  series  of  tests  sample  1  of  an  explosive  of  class  1,  subclass  a — 
an  ammonium-nitrate  explosive  containing  a  sensitizer  that  is  itself 
an  explosive — was  used.  The  cartridges  were  seven-eighths  of  an 
inch  in  diameter.  The  results  were  as  follows : 

Results  of  rate-of-detonation  tests  with  sample  1  of  an  explosive  of  class  1,  subclass  a. 


Grade  of 
electric 
detonator. 

Test  No. 

Rate  of  detonation  in  tube. 

First  quarter.      I    Second  quarter. 

Second  half. 

Full  length. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

No.3  

No.  4  
No.  5  
No.  6  

No.  7  

No.  8  
Gran 

(  M242 
\  M242 
I  M248 

/  M248 
\  M248 

(  D963 
\  D9bO 

{  D966 
\  D967 

f  D964 
\  D965 

/  D968 
\  D969 

d  average. 

Meters  per 
second. 
Detonati< 
3  inches  t 
Detonati< 

Detonatic 
Detonatk 

2,921 
2  inches  t 

2.445 
2,472 

2,777 
2,922 

2,184 
2,250 

Meters  per 
second. 
)n  complel 
down  off; 
)n  complel 

m  complel 
m  complet 

Meters  per 
second. 
e;  16inch< 
16  inches  o 
e;  16incht 

e;  16  inche 
e;  16  inche 

1,956 

f      2,678 
\      2,586 

I      2,586 
\      2,556 

f      2,250 
\      2,320 

Meters  per 
second. 
js  of  explos 
[  explosive 
,s  of  explos 

s  of  explos 
s  of  explos 

20  inches 

j-      2,632 
}      2,571 
}      2,285 

Meters  per 
second. 
ive  used, 
used, 
ive  used. 

ive  used, 
ive  used. 

detonated 

f     2,205 
\      2,205 

/      2,381 
\      2,368 

/      2,472 
\      2,380 

Meters  per 
second. 

\      2,205 
}      2,374 
}      2,426 

Meters  per 
second. 

I      2,368 
\      2,356 

/      2,521 
\      2,535 

/      2,337 
\      2,331 

Meters  per 
second. 

}       2,362 
}       2,528 
}       2,334 

lown  off. 
}     2,458 

}      2,850 
}      2,217 



2,508 

2,496 

2,335 

2,408 

a  For  more  detailed  description  of  this  test,  see  Bull.  15,  Bureau  of  Mines:  Investigations  of  explosives 
used  in  coal  mines;  with  a  chapter  on  the  natural  gas  used  at  Pittsburgh,  by  G.  A.  Burrell,and  an  intro- 
duction by  C.  E.  Munroe,  by  Clarence  Hall,  W.  O.  Snelling,  and  S.  P.  Howell,  1912,  pp.  92-95. 


28   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


No  detonation  occurred  in  those  tests  in  which  2  or  3  inches  of  the 
cartridge  was  blown  off.  In  those  tests  in  which  16  inches  of  the 
explosive  was  used  no  attempt  was  made  to  determine  the  rate  of 
detonation. 

The  grand  average  indicates  that  the  rate  fell  off  in  the  last  half 
meter.  Individual  tests  with  a  given  detonator  showed  remarkable 
uniformity  for  each  electric  detonator  of  Nos.  6,  7,  and  8,  and  with 
No.  6  the  maximum  rate  was  obtained  in  the  second  quarter,  with 
No.  7  in  the  first  quarter,  and  with  No.  8  in  the  second  half.  The 
average  rates  for  the  full  length  of  the  tube  did  not  vary  greatly. 

The  percentage  of  complete  detonations  with  each  detonator  was 
as  follows: 

Percentage  of  complete  detonations  in  rate-of -detonation  tests  with  sample  1  of  an  explosive 

of  class  1,  subclr^  ?. 


Grade  of  electric  detonator. 

Number  of 
tests. 

Number  of 
tests  in  which 
incomplete 
detonation 
occurred. 

Complete 
detona- 
tions. 

No  3 

3 

1 

Per  cent. 
67 

No  4                                                             . 

2 

0 

100 

No  5 

2 

1 

50 

No  6 

2 

0 

100 

No  7 

2 

o 

100 

No  8                               .                     

2 

0 

100 

These  tests  show  that  an  explosive  of  class  1,  subclass  a,  that  is 
insensitive,  tends  more  readily  to  become  completely  detonated  with 
the  higher  grades  of  electric  detonators,  but  that  if  the  explosive 
detonates  at  all  its  rate  is  independent  of  the  grade  of  electric 
detonator  used. 

The  results  of  tests  with  sample  2  of  an  explosive  of  class  1 ,  subclass 
a,  follow.  The  cartridges  used  were  1J  inches  in  diameter. 

Results  of  rate-of -detonation  tests  with  sample  2  of  an  explosive  of  class  1,  subclass  a. 


Grade  of 
electric 
detonator. 

Test  No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

No.3  
No.7  

D1154 
D1155 
D1156 
D1157 
D1158 

D1149 
D1150 
D1151 
D1152 

Meters  per 
second. 
3,090 
2,973 

Meters  per 
second. 

o2,977 
3,324 

Meters  per 
second. 
3,423 
5,946 
5,705 
7,257 
5,488 

4,198 
6,286 
5,  174 
3,134 

Meters  per 
second. 

5,529 

4,698 

Meters  per 
second. 
4,734 
2,973 
3,708 
3,435 
3,516 

3,069 
2,933 
3,739 
3,618 

Meters  per 
second. 

3,664 
3,340 

Meters  per 
second. 
3,854 
3,398 

Meters  per 
second. 

o3,668 
i        3,506 

2.884 
2,960 

3,836 
2,973 
2,649 
3,836 

3,750 
3,673 

3,477 
3,398 
3,618 
3,532 

o  Test  No.  D1156  not  included  in  average. 


INDIRECT  TESTS  OF  P.  T.  S.  S.  ELECTRIC  DETONATORS. 


29 


The  averages  for  each  detonator  show  a  positive  acceleration  in  the 
second  quarter  meter  and  a  negative  acceleration  in  the  second  half 
meter.  The  rates  for  the  meter  length  is  within  the  experimental 
error,  and  they  were,  therefore,  practically  uniform. 

The  results  of  tests  with  sample  3  of  an  explosive  of  class  1 ,  sub- 
class a,  follow.  The  cartridges  used  were  1J  inches  in  diameter. 

Results  of  rate-of -detonation  tests  with  sample  3  of  an  explosive  of  class  7,  subclass  a. 


Grade  of 
electric 
detonator. 

Test  No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

No.3  
No.  7  

{D1161 
D1162 
D1163 

{D1127 
D1128 
D1129 
D1130 

Meters  per 
second. 
a3,143 
4,167 
4,450 

3,477 
3,007 
3,090 
4,231 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

}      4,308 
3,451 

(     3,571 
\      3,  134 

4,045 
4,363 
4,541 
3,729 

\      3,352 
1      4,  170 

/     2,980 
\     3,397 

f      3,450 
3,202 
3,296 
3,359 

}      3,188 
1     3,327 

f     3,488 
\      3,532 

3,589 
3,371 
3,477 
3,636 

}       3,510 
3,518 

a  Detonation  incomplete;  test  not  averaged. 

The  average  rate  for  the  meter  length  was  practically  uniform. 
The  percentage  of  complete  detonations  for  each  electric  detona- 
tor was  as  follows: 

Percentage  of  complete  detonations  in  rate-of-detonation  tests  with  sample  3  of  an  explosive 

of  class  1,  subclass  a. 


Number  of 

Grade  of  electric  detonator. 

Number  of 
tests. 

tests  in 
which 
complete 
detonation 

Complete 
detona- 
tions. 

occurred. 

Per  cent. 

No.3... 

3 

2 

67 

No  7 

4 

4 

100 

TESTS    WITH    AN    EXPLOSIVE    OF   CLASS    1,   SUBCLASS    6 

The  results  of  tests  with  sample  1  of  an  explosive  of  class  1 ,  subclass 
b — an  ammonium-nitrate  explosive  containing  a  sensitizer  that  is 
not  in  itself  an  explosive — follow.  The  diameter  of  the  cartridges 
used  was  If  inches. 

Results  of  rate-of-detonation  tests  with  sample  1  of  an  explosive  of  class  1,  subclass  b. 


Grade  of  electric  detonator. 

Test  No. 

Remarks. 

No.  3 

M237 

No  detonation 

No.  4... 

M237 

Do. 

No.  5.. 

D870 

Do 

No  6 

{D871 
D869 

Do. 
Do 

No  7 

D871 
f      D869 

Do. 
Do. 

No  8 

\       D871 
/      D869 

Do. 
Do. 

\      D871 

Do. 

30   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


These  tests  failed  to  make  a  discrimination  between  the  different 
grades  of  electric  detonators,  and  hence  for  the  purposes  of  this 
investigation  were  useless. 

The  results  of  tests  with  sample  2  of  an  explosive  of  class  1,  sub- 
class &,  follow.  The  cartridges  used  were  If  inches  in  diameter. 

Results  of  rate-of-detonation  tests  vrith  sample  2  of  an  explosive  of  class  1,  subclass  b. 


Grade  of 
electric 
detona- 
tor. 

Test  No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Individ-    Average 
ual  rate.       rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

No  3 

M232 
M241 
M241 
M240 
M240 

M231 
M241 
M241 
M240 
M240 

M240 
M241 
M241 
D923 
D926 

M249 
D930 
D931 
D932 
D1110 

M241 
M241 
D928 
D929 
D956 

M241 
D925 
D927 
D954 
D955 

average. 

Meters  per  Meters  per  Meters  per 
second.      second.      second. 
6  inches  o  f  cartridge  blown  off. 
4inchesofcartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
3  inches  of  cartridge  blown  off. 
3  inches  of  cartridge  blown  off. 

6  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 

4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 
4  inches  of  cartridge  blown  off. 

Detonation  complete;  16  inche 
8  inches  of  cartridge  blown  off. 
3,000)        3,000          3,750 
8  inches  of  cartridge  blown  off. 
5  inches  of  cartridge  blown  off. 

Detonation  complete;  16  niche 
Detonation  complete;  16  inch( 
3,358(1                  II      3,462 
3,462    I      3,384  \\      3,814 
3,333   j                   I      3,491 

Detonation  complete;  16  inche 
2,647  |f                   f      3,214 
3,169    1      o  n79   1      3,750 
3  235   I       3'072  I      3  055 
3,235    (                   I      3,142 

Meters  per 
second. 

s  of  explos 
3,750 

s  of  explos 
ss  of  explos 

1     3,589 
IB  of  explos 
13,290 

Meters  per 
second. 

ive  used. 
3,333 

ive  used, 
ive  used. 
f     3,  743 
\      3,082 
I      3,464 

ive  used. 
f      4,286 
3,147 
3,358 
3  384 

Meters  per 
second. 

3,333 

3,430 
3,544 

Meters  per 
second. 

3,333 

(      3,475 
\      3,333 
I      3,437 

3,462 
3,285 
3,247 
3,283 

Meters  per 
second. 

3,333 

t       3,415 
1       3,319 

No.  4  

No.  5.  ... 

No.  6  
No.7  

No.  8  
Grand 

3,  180 

3,460 

3,475 

3,357 



It  is  probable  that  no  detonation  occurred  in  those  tests  in  which 
3  to  8  inches  of  the  cartridge  was  blown  off.  In  the  trial  listed  under 
test  M  241  only  16  inches  of  explosive  was  used  and  no  attempt  was 
made  to  determine  the  rate  of  detonation. 

The  grand  average  shows  the  tendency  of  the  rate  of  detonation  to 
increase  beyond  the  first  quarter. 

It  is  interesting  to  observe  that  the  rate  of  detonation  for  that  10 
centimeters  of  a  1  J-inch  cartridge  just  beyond  the  electric  detonator, 
as  determined  with  the  cordeau  detonant,  was  as  follows:  For  a  No.  7 
electric  detonator,  3,387  meters  per  second;  for  a  No.  8  electric 
detonator,  3,387  meters  per  second. 


INDIRECT   TESTS  OF   P.   T.   S.   S.   ELECTRIC   DETONATORS. 


31 


The  percentage  of  complete  detonations  for  each  detonator  was  as 
follows: 

Percentage  of  complete  detonations  in  rate-of-detonation  tests  with  sample  2  of  an  explosive 

of  class  1,  subclass  b. 


Number  of 

Grade  of  electric  detonator. 

Number  of 
tests. 

tests  in 
which  in- 
complete 
detonation 

Complete 
detona- 
tions. 

occurred. 

Per  cent. 

No  3 

5 

0 

No  4 

5 

5 

0 

No.  5                                 

5 

5 

0 

No  6 

5 

3 

40 

No.  7.   . 

5 

0 

100 

No.  8                                                         

0 

100 

These  tests  show  that  an  explosive  of  class  1,  subclass  6,  that  is 
insensitive,  tends  more  readily  to  become  completely  detonated  with 
the  higher  grades  of  electric  detonators,  but  that  if  the  explosive 
detonates  at  all  its  rate  is  independent  of  the  grade  of  electric  deto- 
nator used. 

TESTS   WITH  A  20  PER  CENT    "  STRAIGHT "    NITROGLYCERIN  DYNAMITE. 

The  results  of  tests  with  a  20  per  cent  "straight"  nitrogtycerin 
dynamite  follow.  The  cartridges  were  seven-eighths  of  an  inch  in 
diameter. 

Results  of  rate-of-detonation  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite. 


Rate  of  detonation  in  tube. 

Grade  of 
electric 

Test  No. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

detona- 

tor. 

Individ- 

Average 

Individ- 

Average 

Individ- 

Average 

Individ- 

Average 

ual  rate. 

rate. 

ual  rate. 

rate. 

ual  rate. 

rate. 

ual  rate. 

rate. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

Meters  per 
second. 

No.3  

f     D1096 
\    D1097 

2,528 
2,781 

2,  654 

I     3,648 
\      2,  967 

}      3,308 

(      2,  853 
\      3,  156 

}      3,004 

J      2,918 
\     3,007 

}       2,962 

No.  4  

/     D1098 
\    D1099 

2,418 

2,781 

2,600 

1      3,423 

t      2,  967 

}      3,  195 

/      2,834 
I      2,871 

|      2,  852 

/      2,  834 
\      2,871 

j-        2,  852 

No.o  

I       D992 
1       D993 

3,225 
2,747 

1      2,  986 

/      2,  781 
i      2,928 

}      2,854 

I      2,908 
\      2,987 

}•      2,948 

/      2,  947 
\      2,908 

}        2,928 

{D1000 

3,729 

1 

{2,683 

1 

{2,767 

} 

{2,933 

) 

No.6  

D1001 

o3,034 

\      3,838 

3,034 

}      2,563 

3,121 

^      3,038 

3,077 

\        3,046 

D1002 

3,947 

[ 

2,443 

j 

3,309 

I 

3,158 

1 

No.7  

J     D1003 
\     D1004 

3,836 
3,125 

}      3,  480 

(      2,500 
\      2,  586 

j-      2,  543 

/      2,  947 
\      3,  192 

j-      3,  070 

/      2,  986 
\      3,000 

I        2,993 

No.8  

I     D1005 
\     D1006 

3,358 
3,261 

j      3,310 

/      2,679 
\      2,  778 

}      2,728 

/      2,980 
\      3,041 

|      3,010 

I      2,980 
\      3,020 

|        3,000 

Grand  average. 

3,145 

2  865 

2,987 

2,964 

a  Average  rate  for  the  first  half  meter;  rate  not  included  in  average. 
7S8750— Bull.  59—13 3 


32   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


In  the  tests  where  electric  detonators  Nos.  3,  4,  and  5  were  used  a 
considerably  lower  rate  of  detonation  occurred  in  the  first  quarter  than 
in  the  tests  where  electric  detonators  Nos.  6,  7,  and  8  were  used. 

Detonation  was  complete  with  every  grade  of  electric  detonator. 

The  figures  in  the  grand  average  indicate  that  the  rate  was  influ- 
enced by  a  negative  acceleration  in  the  second  quarter  meter,  followed 
by  a  positive  acceleration  in  the  second  half  meter,  though  the  con- 
trary was  true  for  electric  detonators  of  grades  Nos.  3  and  4.  All 
tests  except  test  D993  conformed  to  this. 

The  uniformity  of  the  rates  for  the  last  half  meter  and  for  the 
meter  for  every  grade  are  noteworthy;  this  uniformity  held  for  indi- 
vidual tests  as  well  as  for  averages. 

TESTS  WITH  A  40  PER  CENT  STRENGTH  AMMONIA  DYNAMITE  CONTAINING 
NITROSUBSTITUTION   COMPOUNDS. 

The  results  of  tests  with  a  40  per  cent  strength  ammonia  dynamite 
containing  nitrosubstitution  compounds  follow.  The  cartridges  used 
were  seven-eighths  of  an  inch  in  diameter  and  had  been  repacked. 

Results  of  rate-of-detonation  tests  with  a  40  per  cent  strength  ammonia  dynamite  contain- 
ing nitrosubstitution  compounds. 


Grade  of 
electric 
detonator. 

Test  No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Individ- 
ual rate 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

No.  5  
No.  6  

No.  7  

No.8  

aD878 
D882 
D903 
D921 

oD875 
D904 
aD905 
D919 
D920 

oD873 
D906 
«D907 
D918 
D959 

/    «D872 
D881 
D910 
D911 
oD915 
D916 
I      D917 

Meters  per 
second. 

Meters  per 
second. 

2,498 
2,363 

2,543 
2,310 

Meters  per 
second. 

*"*3,"  929" 
2,586 
2,528 

Meters  per 
second. 

3,014 
2,594 

2,709 
3,  146 

Meters  per 
second. 

Meters  per 
second. 

|      2,286 
I      2,593 

2,619 

2,755 

Meters  per 
second. 
2,811 
2,350 
2,446 
2,439 

2,659 
2,446 
2,521 
2,695 
2,439 

2,658 
2,557 
2,641 
2,647 
2,619 

2,514 
2,597 
2,561 
2,557 
2,195 
2,795 
2,752 

Meters  per 
second. 

2,412 
2,527 

2,608 
2,652 

2.136 
2,679 
2,679 

o    AAA 
O,  ODD 

2.368 
c2,285 
2,472 
2,250 

2,631 
2,394 
c2,367 
2,616 
2,619 

2,716 
2,558 
1^542 
2,123 

2,045 
2,284 
.      2,528 

62,435 
2,572 
2,813 
2,663 
.      2,543 

'62,668 
2,830 
2,987 
2,528 
2,500 

(    62,453 
2,280 
3,345 
2,711 

2,296 

3,041 
2,446 

2,273 

2,961 
2,894 

3,667 
3,209 
2,815 

2,679 
2,647 

3,041 
3,000 

2,744 
I      2,695 

o  Rate  of  detonation  not  averaged. 
&  Rate  for  last  three-fourths  of  a  meter. 
c  Rate  for  first  one-half  of  a  meter. 


INDIRECT   TESTS  OF   P.   T.   S.   S.   ELECTRIC  DETONATORS. 


33 


No  tests  were  made  with  electric  detonators  Nos.  3  and  4.  The 
average  rate  for  the  meter  length  increased  slightly  with  the  grade 
of  electric  detonator  used.  The  fastest  rate  is  recorded  for  the  second 
quarter  meter.  The  figures  for  the  average  rates  and  for  most 
of  the  individual  tests  indicate  that  the  rate  increased  up  to  a  maxi- 
mum, and  then  decreased.  With  some  electric  detonators  the  maxi- 
mum was  reached  in  the  first  quarter  meter,  as  in  test  D903;  with 
others  in  the  second  quarter  meter,  as  in  test  D919;  and  with  others 
in  the  second  half  meter,  as  in  test  D910. 

If  it  be  assumed  that  the  recorded  rate  was  slightly  erratic,  but 
had  a  general  tendency  to  increase  to  a  maximum,  and  then  to  decrease 
toward  an  asymptotic  normal  rate,  then  the  results  of  all  the  tests 
conformed  to  this  assumption. 

TESTS    WITH    A    40    PER    CENT    STRENGTH    AMMONIA   DYNAMITE. 

The  results  of  tests  with  a  40  per  cent  strength  ammonia  dynamite 
follow.  The  cartridges  used  were  1J  inches  in  diameter. 

Results  of  rate-of -detonation  tests  with  a  40  per  cent  strength  ammonia  dynamite. 


Grade  of 
electric 
detonator. 

Test  No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

Individ- 
ual rate. 

Average 
rate. 

No.  3  

f     D1139 
\     D1140 
I     D1141 

Meters  per 
second. 
4,018 
4,327 
3,516 

Meters  per 
second. 

3,954 

Meters  per 
second. 
f      4,412 
\      4,592 
I      4,592 

Meters  per 
second. 

4,532 

Meters  per 
second. 
f       ,545 
\        ,054 
I        ,128 

\fetcrsper 
second. 

4,242 

Meters  per 
second. 
f      4,369 
\      4,245 
I      4,054 

Meters  per 
second. 

4,223 

No.  8  

1D1136 
D1137 
D1138 

3,437 
3,250 
3,750 

•      3,479 

{4,314 
5,291 
5,000 

4,868 

f        ,889 
I        ,417 
|      3,982 

4,429 

f      4,293 
\      4,213 
I      4,128 

4,211 

Only  the  No.  3  and  the  No.  8  electric  detonators  were  used.  The 
average  rate  for  the  meter  length  is  practically  the  same  for  the 
two  detonators.  The  rate  increased  to  a  maximum  in  the  second 
half  meter  and  then  decreased  as  shown  by  averages;  the  results  of 
individual  tests  confirm  this  conclusion.  The  rate  in  the  last  half 
meter  corresponded  closely  with  the  average  rate  for  the  meter  length. 

TESTS    WITH    A   35  PER   CENT    STRENGTH     GELATIN    DYNAMITE    2    YEARS 

OLD. 

The  results  of  tests  with  a  35  per  cent  strength  gelatin  dynamite 
(2  years  old)  follow.  The  cartridges  used  were  1J  inches  in 
diameter. 


34    INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 

Results  of  rate-of -detonation  tests  with  a  35  per  cent  strength  gelatin  dynamite  (2  years  old). 


Grade  of  electric  detonator. 

Test  No. 

Length  of 
files  blown 
off  or  deto- 
nated. 

Percentage 
inches  that 
detonated. 

Average 
percent- 
age that 
deto- 
nated. 

Remarks. 

No  3 

M231 

Inches. 
6.5 

Per  cent. 
15 

Per  cent. 
15.0 

Partial  detonation. 

No.  4.. 
No  5 

M234 

D887 

7.5 
7.0 

18 
0 

18.5 

Do. 
No  detonation. 

D888 

7  0 

0 

Do. 

No.6  

D942 
D943 
D889 

13.0 
13.0 

7.0 

31 
31 

0 

""is.  5 

Partial  detonation. 
Do. 
No  detonation. 

D896 

18.0 

43 

Partial  detonation. 

No  7 

D958 
D890 

17.0 
12.0 

40 
29 

28.0 

Do. 
Do. 

D895 

12  0 

29 

Do. 

No  8 

D957 
D891 

12.0 
18.0 

29 
43 

29.0 

Do. 
Do. 

D892 

12.0 

29 

Do. 

D940 

15  0 

36 

Do. 

D941 

14.0 

33 

35 

Do. 

a  Full  length  of  file,  42  inches. 

The  evidence  of  no  detonation  in  tests  D887,  D888,  and  D889 
was  that  nothmg  but  the  noise  of  the  detonator  was  audible  when  the 
trials  were  made. 

In  tests  M231  and  M234  an  8-inch  cartridge  was  used. 

In  no  trial  was  more  than  18  inches  of  the  42  inches  detonated. 
The  part  that  detonated,  in  general,  varied  directly  with  the  grade  of 
the  detonator. 

The  number  of  partial  detonations  with  each  detonator  was  as 
follows: 

Number  of  partial  detonations  in  rate-of-detonation  tests  with  a  35  per  cent  strength  gelatin 

dynamite  (2  years  old). 


Grade  of  electric  detonator. 

Number  of 
tests. 

Number  of 
tests  in 
which  partial 
detonation 
occurred. 

Percentage 
of  partial 
detona- 
tions. 

No  3 

1 

Per  cent. 
100 

No  4 

2 

2 

100 

No  5                                                       

4 

2 

50 

No  6 

3 

2 

67 

No  7                                                    

3 

3 

100 

No  8 

4 

4 

100 

Except  with  the  No.  3  and  the  No.  4  electric  detonators,  the  number 
of  tests  with  which  was  small,  the  percentage  of  partial  detonations 
increased  with  the  grade  of  the  electric  detonator. 


INDIRECT  TESTS  OF  P.  T.  S.   S.  ELECTRIC  DETONATORS. 


35 


TESTS    WITH    A    40   PER   CENT    STRENGTH    GELATIN   DYNAMITE,   FROZEN. 

The  results  of  tests  with  a  40  per  cent  strength  gelatin  dynamite 
(frozen)  follow.     The  diameter  of  the  cartridges  used  was  If  inches. 

Results  of  rate-of-detonation  tests  with  a  40  per  cent  strength  gelatin  dynamite  (frozen). 


Grade  of  electric  detonator. 

Test  No. 

Rate  of  detonation. 

First 
quarter. 

Second 
quarter. 

Second 
half. 

Total. 

No  3o 

D1087 
D1088 
D1089 
D1093 
D1094 
D1095 

Meters  per 
second. 
3  inches  bio 
4,018 
6,250 
4,167 
4,687 
4,018 

Meters  per 
second. 
wnoff. 
6,429 
7,258 
7,759 
6,429 
7,500 

Meters  per 
second. 

5,890 
5,769 
6,522 
5,769 
6,522 

Meters  per 
second. 

5,376 
6,207 
5,921 
5,591 
5,806 

No.  4 

No  5 

No.  6 

No.  7  

No.  8 

Grand  average    

4,628 

7,075 

6,094 

5,780 

a  No  detonation  occurred  with  the  No.  3  electric  detonator. 

The  grand  averages  show  that  the  maximum  rate  occurred  in  the 
second  quarter,  with  a  subsequent  falling  off  in  the  rate;  moreover, 
each  individual  test  showed  similar  results,  irrespective  of  the  grade 
of  the  electric  detonator  used. 

The  variation  of  14.4  per  cent  in  the  average  rate  is  rather  high, 
and  is  seemingly  due  to  the  fact  that  results  with  frozen  explosives 
are  always  erratic. 

Complete  detonation  occurred  in  each  test  with  each  of  the  six 
electric  detonators  except  the  No.  3,  which  failed  to  detonate. 

TESTS    WITH    A    35    PER    CENT    STRENGTH    GELATIN    DYNAMITE 

3  YEARS   OLD. 

The  results  of  tests  with  a  35  per  cent  strength  gelatin  dynamite 
(three  years  old)  follow.  The  cartridges  used  were  1J  inches  in 
diameter. 

Results  of  rate-of-detonation  tests  with  35  per  cent  strength  gelatin  dynamite  (3  years  old). 


Grade  of  electric  detonator. 

Test  No. 

Remarks. 

No.  3 

M238 

No.  4... 

M238 

Do 

No.  5 

D868 

Do 

No.  7... 

D866 

Do 

No.  8  

D865 

Do 

The  explosive  was  so  old  and  insensitive  to  detonation  that  for 
the  purpose  of  discriminating  between  grades  of  electric  detonators 
it  was  useless,  because  in  no  test  did  detonation  occur.  No  tests 
were  made  with  the  No.  6  electric  detonator. 


INVESTIGATIONS  OF   DETONATORS  AND  ELECTRIC   DETONATORS. 


SMALL  LEAD  BLOCK  TESTS.« 

The  lead  blocks  used  in  the  small  lead  block  tests  were  squirted  with 
a  diameter  of  1J  inches  and  were  cut  to  a  length  of  2£  inches.  An 
annealed  steel  disk  1 1  inches  in  diameter  and  one-quarter  inch  high 
was  placed  above  each  block  and  above  this  was  placed  the  100-gram 
charge  of  the  explosive,  held  in  position  by  a  paper  sleeve  wrapped 
around  the  block  and  the  disk  and  extending  above  them.  The 
electric  detonator  used  was  centrally  placed  in  the  top  of  the  charge. 
When  the  explosion  was  fired,  the  block  rested  on  a  firm  horizontal 
steel  base.  The  compression  of  the  block  was  determined  by  measur- 
ing the  difference  in  the  height  of  the  block  before  and  after  firing. 

TESTS    WITH   A   20   PER   CENT    "  STRAIGHT"    NITROGLYCERIN    DYNAMITE 
WITH   6    PER    CENT    OF   ADDED   WATER. 

The  results  of  tests  of  a  20  per  cent  " straight"  nitroglycerin  dyna- 
mite follow.  The  explosive  contained  6  per  cent  of  added  water: 

Results  of  small  lead  block  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite  con- 
taining 6  per  cent  of  added  water. 


Grade  of  electric  detonator. 

Test  No. 

Com- 
pression. 

!  Aver  age 
com- 
pression. 

No.  3  .-  

B755 

Mm. 
14.00 

Mm. 

' 

No  4 

B764 
B773 

B756 

14.25 
14.00 

15  00 

14.08 

No.  5  

B765 
B774 

B757 

14.50 
14.50 

14.25 

14.67 

No.  6  

B766 
B775 

B761 

14.00 
14.00 

15.00 

14.08 

No  7 

B770 
B779 

B762 

15.00 
15.00 

15  25 

.. 

iis.oo 
. 

No.  8 

B771 
B780 

B763 

14.75 
15.75 

15  50 

15.25 

B772 
B781 

15.75 
15.25 

15.50 

The  No.  8  electric  detonator  produced  a  compression  9.6  per  cent 
greater  than  that  of  the  No.  3  electric  detonator;  in  general  with  the 
explosive  tested,  the  compression  increased  with  the  grade  of  the 
detonator.  The  No.  4  electric  detonator,  however,  developed  more 
energy  than  did  the  No.  5. 

o  For  a  more  extended  description  of  the  small  lead  block  test,  see  Bull.  15,  Bureau  of  Mines:  Investi- 
gations of  explosives  used  in  coal  mines;  with  a  chapter  on  the  natural  gas  used  at  Pittsburgh,  by  G.  A. 
Burrell,  and  an  introduction  by  C.  E.  Monroe,  by  Clarence  Hall,  W.  O.  Snelliug,  and  S.  P.  Howell,  1912, 
pp.  113-114. 


INDIRECT  TESTS  OF  P.  T.   S.   S.  ELECTRIC  DETONATORS. 


37 


TESTS   WITH   A   20   PER   CENT  , 

FROZEN  AND  CONTAINING  LESS  THAN  6  PER  CENT  OF  ADDED  WATER. 

The  results  of  tests  with  a  20  per  cent  "straight"  nitroglycerin 
dynamite  (frozen  and  containing  no  added  water  or  2.5  or  4  per  cent 
of  added  water)  are  tabulated  below: 

Results  of  small  lead  block  tests  of  a  20  per  cent  "straight"  nitroglycerin  dynamite  (frozen 
and  containing  less  than  6  per  cent  of  added  water). 


Grade  of  electric  detonator. 

Test  No. 

Temper- 
ature of 
frozen 
explosive. 

Percent- 
age of 
added 
water. 

Com- 
pression. 

Average 
com- 
pression. 

No  3                                                                      .     .. 

B616 

•c. 

+2.0 

0 

Mm. 
14.25 

Mm. 

No  4                             

B622 
B647 

B617 

-1.0 
-9.0 

+2.0 

2.5 

4.0 

0 

13.25 
12.50 

14.50 

13.33 

No  5 

B623 
B648 

B618 

-1.0 
-9.0 

+2.0 

2.5 

4.0 

0 

13.25 
12.50 

13.50 

13.42 

No  6                                                                         

B624 
B649 

B619 

-1.0 
-9.0 

+2.0 

2.5 

4.0 

0 

13.00 
12.50 

13.50 

13.00 

No  7                               

B625 
B653 

B620 

-1.0 
-9.0 

+2.0 

2.5 

4.0 

0 

13.25 
13.00 

15.00 

13.25 

No  8 

B625 
B654 

B621 

-1.0 
-9.0 

+2.0 

2.5 

4.0 

0 

13.50 
13.00 

15.25 

13.83 

B627 
B655 

-1.0 
-9.0 

2.5 
4.0 

13.25 
13.25 

13.92 

The  tests  showed  the  tendency  of  the  electric  detonators  to  increase 
slightly  in  explosive  efficiency  with  the  grade,  but  again  the  No.  3 
and  the  No.  4  electric  detonators  showed  an  increase  over  the  No.  5 
and  even  over  the  No.  6. 

TESTS   WITH   A    20    PER   CENT  "  STRAIGHT"  NITROGLYCERIN   DYNAMITE, 
FROZEN    AND    CONTAINING    6    PER    CENT   OF   ADDED   WATER. 

As  no  failures  had  occurred  with  any  of  the  electric  detonators, 
when  tested  with  the  20  per  cent  " straight"  nitroglycerin  dynamite, 
a  sample  of  that  explosive  with  6  per  cent  of  added  water  was  frozen 
(temperature  9°  C.)  and  was  tested,  with  results  as  follows: 

Results  of  small  lead  block  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite  (frozen 
and  containing  6  per  cent  of  added  water). 


Grade  of  electric  detonator. 

Test  No. 

Compres- 
sion. 

Average 
compres- 
sion. 

No  3 

B728 

Mm. 
oO.OO 

Mm. 

No  4 

B737 
B746 

B729 

.00 
.00 

.00 

0.00 

B738 
B747 

.00 
.00 

.00 

a  Incomplete  deto  nation. 


38   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


Results  of  small  lead  block  tests  with  a  20  percent  "straight"  nitroglycerin  dynamite 
(frozen  and  containing  6  per  cent  of  added  water)—  Continued. 


Grade  of  electric  detonator. 

Test  No. 

Compres- 
sion. 

Average 
compres- 
sion. 

No.  5  

B730 

Mm. 
aQ  00 

Mm. 
) 

No.  6 

B739 
B748 

B734 

a.  00 
a.  00 

a  00 

0.00 
1 

No.  7.. 

B743 
B752 

B735 

«.oo 

a.  00 
12  75 

1    •« 

1 

No.  8  

B744 
B753 

B736 

13.75 
a.  50 

12.75 

9.00 
I 

B745 
B754 

13.75 
a  1.00 

9.17 

a  Incomplete  detonation. 

The  number  of  complete  detonations  with  each  detonator  was  as 
follows : 

Number  of  complete  detonations  with  a  20  per  cent  "straight"  nitroglycerin  dynamite 
(frozen  and  containing  6  per  cent  of  added  water). 


Number 

of  tests  in 

Percentage 

Grade  of  electric  detonator. 

Number  of 
tests. 

which 
complete 

of  complete 
detona- 

detonation 

tions. 

occurred. 

No.  3. 

3 

0 

0 

No  4 

3 

c 

0 

No.  5  

3 

0 

0 

No.  6 

3 

o 

0 

No.  7  

3 

2 

07 

No.  8 

3 

2 

07 

The  explosive  was  very  insensitive  and  complete  detonation 
occured  only  with  the  No.  7  and  No.  8  electric  detonators  and  with 
them  in  only  two  out  of  three  trials  with  each. 

TESTS    WITH     A     40    PEE     CENT     STRENGTH    AMMONIA     DYNAMITE    WITH 
6    PER    CENT    OF    ADDED    WATER. 

The  results  of  tests  with  a  40  per  cent  strength  ammonia  dynamite 
with  6  per  cent  of  added  water  are  tabulated  below: 

Results  of  small  lead  block  tests  with  a  40  per  cent  strength  ammonia  dynamite  containing 

6  per  cent  of  added  water. 


Grade  of  electric  detonator. 

Test  No. 

Compres- 
sion. 

Average 
compres- 
sion. 

No.  3 

B656 

Mm. 
7  25 

Mm. 

1' 

B665 
B674 
BG83 
B692 

8.50 
9.50 
8.25 

7.75 

8.25 

INDIRECT  TESTS  OF  P.  T.  S.  S.  ELECTRIC  DETONATORS. 


39 


Results  of  small  lead  block  tests  with  a  40  per  cent  strength  ammonia  dynamite  containing 
6  per  cent  of  added  water — Continued. 


Grade  of  electric  detonator. 

Tost  No. 

Compres- 
sion. 

Average 
compres- 
sion. 

No.  4                                           • 

B657 

Mm. 
7.25 

Mm. 

No  5 

B666 
B675 
BC84 
B693 

B658 

8.75 
8.50 
8.00 
8.50 

6.00 

8.20 

V 

No  6 

B667 
B676 
B685 
B694 

B662 

7.25 
8.75 
8.00 
8.50 

9  75 

7.70 

No.  7  

B671 
B680 
B689 
B698 

B663 

8.75 
9.25 
7.75 
9.25 

8.00 

8.95 

No.  8                                                                   

B672 
B681 
,  B690 
B699 

B664 

8.75 
10.00 
10.25 
8.75 

8.75 

9.15 

B673 
B682 
B691 
B700 

9.50 
10.75 
9.75 
9.75 

9.70 

This  explosive  showed  a  marked  tendency  to  be  erratic  both  with 
the  higher  and  with  the  lower  grades  of  electric  detonators. 

The  explosive  efficiency  of  the  electric  detonators  increased  with 
the  grade  of  the  electric  detonator,  except  that  the  efficiency  of  the 
No.  5  electric  detonator  was  considerably  low  and  that  of  the  No.  3 
a  trifle  high. 

TESTS  WITH  A  40  PER  CENT    STRENGTH    GELATIN    DYNAMITE,    FROZEN. 

Following  are  the  results  (PL  V,  A)  of  tests  with  a  40  per  cent 
strength  gelatin  dynamite  that  was  in  a  frozen  condition: 

Results  of  small  lead  block  tests  with  a  40  per  cent  strength  gelatin  dynamite  (frozen). 


Grade  of  electric  detonator. 

Test  No. 

Tempera- 
ture of 
frozen 
explosive. 

Compres- 
sion. 

Average 
compres- 
sion. 

No.3  

B633 

°C. 
—2.5 

Mm. 
03.00 

Mm. 

No.  4  

B638 
B701 
B710 
B719 

B629 

-5.0 
+0.5 
+2.5 

+2.5 

—4.5 

16.75 
13.00 
13.  50 
13.75 

a  1.50 

1           14.25 

No.  5  

B639 
B702 
B711 
B720 

B630 

-5.0 

+0.5 
+2.5 
+2.5 

—4.5 

15.50 
10.75 
11.00 
13.25 

a  1.00 

12.62 

BC40 
B703 
B712 
B721 

-5.0 
+0.5 
+2.5 
+2.5 

17.25 
13.75 
10.75 
10.75 

13.12 

a  Incomplete  detonation. 


40   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS, 

Results  of  small  lead  block  tests  with  a  40  per  cent  strength  gelatin  dynamite  (frozen] — Con. 


Grade  of  electric  detonator. 

Test  No. 

Tempera- 
ture of 
frozen 
explosive. 

Compres- 
sion. 

Average 
compres- 
sion. 

No.  6  

B631 

°a 

—4  5 

Mm. 
12  50 

Mm. 

No.  7 

B644 
B707 
B716 
B725 

B632 

-5.0 
+0.5 
+2.5 
+2.5 

4  5 

19.25 
14.25 
14.25 
14.50 

14  50 

14.95 

No.  8           ...             .      . 

B645 
B708 
B717 
B726 

B637 

-5.0 

+0.5 
+2.5 
+2.5 

—2  5 

20.25 
18.00 
16.25 
16.00 

15  75 

17.00 

B646 
B709 
B718 
B727 

-5.0 
+0.5 
+2.5 
+2.5 

18.00 
19.75 
17.25 
18.25 

17.80 

The  results  were  yery  erratic.  The  strength  of  the  detonators 
increased  with  the  grade  of  the  electric  detonator  used,  as  shown  by 
the  average  compression,  except  that  the  compression  with  the  No.  3 
electric  detonator  was  comparatively  high. 

The  number  of  complete  detonations  with  each  detonator  was  as 
follows : 

Number  of  complete  detonations  in  small  lead  block  tests  with  a  40  per  cent  strength  gelatin 

dynamite  (frozen). 


Grade  of  electric  detonator. 

Number  of 

tests. 

Number  of 
tests  in  which 
complete 
detonation 
occurred. 

Percentage 
of  complete 
detona- 
tions. 

No.  3... 

5 

4 

Per  cent. 
80 

No.  4 

5 

4 

80 

No.  5... 

5 

4 

80 

No.  6 

5 

5 

100 

No.  7... 

5 

5 

100 

No.  8 

5 

5 

100 

The  results  tabulated  above  indicate  that  the  tendency  to  complete 
detonation  increases  with  the  grade  of  the  electric  detonator  used. 

EXPLOSION-BY-INFLTJENCE  TESTS/* 

Explosion-by-influence  tests  were  conducted  by  placing  two  car- 
tridges of  an  explosive  at  a  definite  distance  apart;  each  cartridge 
was  in  a  vertical  position,  one  being  directly  above  the  other.  The 
electric  detonator  was  placed  in  the  lower  end  of  the  lower  cartridge, 
so  that  the  lower  cartridge  on  detonation  either  did  or  did  not  cause 

«  For  a  more  extended  description  of  the  test,  see  Bull.  15,  Bureau  of  Mines:  Investigations  of  explo- 
sives used  in  coal  mines;  with  a  chapter  on  the  natural  gas  used  at  Pittsburgh,  by  G.  A.  Burrell,  and  an 
introduction  by  C.  E.  Munroe,  by  Clarence  Hall,  W.  O.  Snelling,  and  S.  P.  Howell,  1912,  p.  100. 


BUREAU    OF    MINES 


BULLETIN    59      PLATE   V 


A.     RESULTS  OF  SMALL  LEAD   BLOCK  TESTS  OF  P.  T.  S.  S.  ELECTRIC  DETONATORS  NOS.  3,  4,  5, 
6,  7,  AND  8.     a,   BLOCK  BEFORE  TEST. 


B.     RESULTS  OF  SMALL  LEAD  BLOCK  TESTS  OF  NO.  6  ELECTRIC  DETONATORS,     a,   BLOCK 
BEFORE  TEST;  6,  WESTERN  COAST;  c,  SPECIAL;  d,  P.  T.  S.  S.;  e,  FOREIGN. 


WESTERN  COAST. 


SPECIAL. 


P.  T.  S.  S.  FOREIGN. 

C.     SCORING  OF  LEAD  PLATES  BY  FOUR  NO.  6  ELECTRIC  DETONATORS  LAID  ON  SIDE. 


INDIRECT   TESTS  OF   P.   T.   S.   S.   ELECTRIC   DETONATORS, 


41 


detonation  of  the  upper  cartridge.  The  separating  distance,  estab- 
lished by  successive  trials,  was  but  1  inch  greater  than  that  at  which  the 
upper  cartridge  would  detonate.  With  one  explosive,  however,  certain 
trials  were  run  with  the  cartridges  separated  by  a  given  distance,  and 
the  number  of  times  that  the  upper  cartridge  did  or  did  not  detonate 
was  recorded. 

TESTS    WITH    AN    EXPLOSIVE    OF    CLASS    1,    SUBCLASS  a. 

The  results  of  tests  with  an  explosive  of  class  1,  subclass  a  (an 
ammonium-nitrate  explosive  containing  a  sensitizer  that  is  itself  an 
explosive),  are  tabulated  below.  The  average  weight  of  the  car- 
tridges was  166  grams  and  they  measured  1J  by  8  inches. 

Results  of  explosion-by -influence  tests  with  an  explosive  of  class  1,  subclass  a. 


Grade  of  electric  detonator. 

Test  No. 

Distance 
separating 
cartridges. 

Result  on  upper 
cartridge. 

Distance 
established 
at— 

No.  3  

J874 

Inches. 
3 

Did  not  explode.  .  . 

Inches. 

); 

J875 
J876 

2 
3 

Exploded  
do 

, 

J877 
J878 

4 
4 

Did  not  explode... 
do  

No.  4                                     .                     

J870 

2 

Exploded  . 

No.  5 

J871 
J872 
J873 

J764 

3 

4 

4 

2 

do  

Did  not  explode... 
do  

do  .. 

• 

J765 

1 

Exploded  

2 

No.  6  

1766 
J741 

2 

4 

Did  not  explode... 
..  do... 

J742 
J743 

3 
2 

do  
do  

J744 

1 

Exploded 

3 

J745 

2 

do  

No.  7  

J746 
J747 

3 
3 

Did  not  explode... 
do 

1 

No.  8 

J748 
J749 

J750 

2 
3 

3 

Exploded  
Did  not  explode... 

do 

I         3 

)" 

J751 
J752 

2 
3 

Exploded  
Did  not  explode... 

3 

These  tests  did  not  discriminate  as  to  the  relative  efficiency  of  the 
different  grades  of  electric  detonators;  the  efficiency  of  the  low-grade 
electric  detonators  was  at  least  as  great  as  that  of  the  high-grade 
electric  detonators. 

TESTS   WITH   AN   EXPLOSIVE    OF   CLASS   4. 

Following  are  the  results  of  tests  with  an  explosive  of  class  4  (an 
explosive  in  which  the  characteristic  material  is  nitroglycerin). 
Except  for  the  trials  under  test  J896,  the  average  weight  of  each 
cartridge  was  161  grams  and  the  size  of  each  was  l£  by  8  inches.  In 
the  trials  under  test  J896  the  lower  cartridge  weighed  161  grams  and 
the  upper  one  weighed  110  grams,  being  only  5  inches  long.  In  all 


42   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


of  the  tests  in  which  the  distance  separating  cartridges  was  5  inches, 
the  bottoms  of  the  cartridges  (as  packed)  faced  each  other,  whereas 
in  all  of  the  tests  in  which  the  separating  distance  was  4  inches,  the 
tops  of  the  cartridges  faced  each  other. 

Results  of  explosion-by-influence  tests  with  an  explosive  of  class  4. 


Grade  of  electric  detonator. 

Test  No. 

Distance 
separating 
cartridges. 

Result—  upper 
cartridge. 

No.  3  
No.  4. 

J895 
J895 
J895 
J895 
J896 
J896 
J896 

J895 

Inches. 
5 
5 
5 
5 
4 
4 
4 

5 

Did  not  explode. 
Do. 
Exploded. 
Did  not  explode. 
Do. 
Do. 
Do. 

Do. 

No  5 

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 
5 
5 
4 
4 
4 

5 

Do. 
Do. 
Exploded. 
Do. 
Do. 
Did  not  explode. 

Do 

No.  6.             .  . 

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 
5 
5 
4 
4 
4 

5 

Do. 
Do. 
Exploded. 
Did  not  explode. 
Do. 
Do. 

Do. 

No.  7. 

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 
5 
5 
4 
4 
4 

Do. 
Do. 
Exploded. 
Do. 
Do. 
Did  not  explode. 

Do 

No.8  

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 
5 
5 
4 
4 
4 

5 

Do. 
Do. 
Exploded. 
Do. 
Do. 
Did  not  explode. 

Do 

J895 
J895 
J895 
J896 
J896 
J896 

5 
5 
8 
4 
4 
4 

Do. 
Do. 
Do. 
Do. 
Exploded. 
Do. 

The  following  tabulation  shows  the  number  of  explosions  of  the 
upper  cartridge: 

Percentage  of  explosions  of  the  upper  cartridge  in  explosion-by-influence  tests  with  an 

explosive  of  class  4- 


Grade  of  electric  detonator. 

Number  of 
tesls. 

Number  of 
explosions  of 
the  second 
cartridge. 

Percentage 
of  explo- 
sions. 

No.  3... 

7 

1 

14 

No.  4 

7 

3 

43 

No.  5... 

7 

1 

14 

No.  6. 

7 

3 

43 

No  7 

7 

3 

43 

No.8  ..      . 

7 

2 

29 

INDIRECT  TESTS  OF  P.  T.  S.  S.  ELECTRIC  DETONATORS. 


43 


TESTS  WITH  A  40  PER  CENT  STRENGTH  AMMONIA  DYNAMITE  CONTAINING 
NITROSUBSTITUTION    COMPOUNDS. 

Following  are  tabulated  the  results  of  tests  with  a  40  per  cent 
strength  ammonia  dynamite  containing  nitrosubstitution  com- 
pounds. The  cartridges  used  were  1J  by  8  inches,  their  average 
weight  being  226  grams. 

Results  of  explosion-by -influence  tests  with  a  40  per  cent  strength  ammonia  dynamite  con- 
taining nitrosubstitution  compounds. 


Grade  of  electric  detonator. 

Test  No. 

Distance 
separating 
cartridges. 

Result  on  upper 
cartridge. 

Distance 
established 
at— 

No  5              

J708 

Inches. 

8 

Exploded  

Inches. 

No  6 

J709 
J710 

J689 

9 
9 

14 

Did  not  explode.  .  . 
do  .(  

...do... 

9 

J690 

12 

do. 

J691 

9 

do  

J692 
J693 
J694 

7 
6 
4 

do  
do  
Exploded 

g 

• 

J695 
J696 
J697 

5 

6 

7 

do  
do  
...do  

J698 
J699 

8 
8 

Did  not  explode.  .  . 
.;.  .do...  

No.  7  

J720 

9 

do  

) 

No  8 

J721 
J722 

J704 

8 
9 

8 

Exploded  
Did  not  explode... 

Exploded 

1        ' 

J705 
J706 
J707 

9 
10 
10 

do  
Did  not  explode... 
do  

10 

No  tests  made  with  detonators  Nos.  3  and  4. 

TESTS  WITH  A  35  PER    CENT    STRENGTH    GELATIN    DYNAMITE    2    YEARS 

OLD. 

Following  are  the  results  of  tests  with  a  35  per  cent  strength 
gelatin  dynamite  (two  years  old).  The  average  weight  of  each 
cartridge  was  265  grams  and  the  size  of  each  1  i  by  8  inches. 

Results  of  explosion-by -influence  tests  with  a  35  per  cent  strength  gelatin  dynamite 

(2  years  old). 


Grade  of  electric  detonator. 

Test  No. 

Distance 
separating 
cartridges. 

Result  on  upper 
cartridge. 

No.  6. 

J724 

Inches. 

6 

No.  7  

J725 
J726 
J727 
J728 
J729 

J730 

5 
4 
2 
0 
0 

o 

Do. 
Do. 
Do. 
Do. 
Do. 

Do 

No.  8.  . 

J731 
J732 

0 

o 

Do. 
Do 

J733 

0 

Do. 

44   INVESTIGATIONS  OF  DETONATOKS  AND  ELECTRIC  DETONATORS. 


No  tests  were  made  with  the  No.  3,  the  No.  4,  or  the  No.  5  electric 
detonators. 

The  tests  failed  to  discriminate  between  the  different  grades  of 
electric  detonators,  except  to  the  limited  extent  that  in  two  trials 
the  lower  cartridge  failed  to  detonate  completely  once  with  the  No. 
6.  In  no  trial  did  the  detonation  of  the  lower  cartridge  cause  the 
detonation  of  the  upper  cartridge. 

PERCENTAGES  OF  DETONATIONS  IN  INDIRECT  TESTS  OF  P.  T.  S.  S. 
ELECTRIC  DETONATORS. 

The  percentages  of  detonations  in  the  indirect  tests  of  the  P.  T.  S.  S. 
electric  detonators  are  given  below.  The  percentages  of  detonations 
in  the  tests  of  each  electric  detonator  are  also  averaged,  each  average 
percentage  having  a  value  proportional  to  the  number  of  tests  from 
which  computed;  that  is,  each  percentage  is  multiplied  by  the  num- 
ber of  tests  it  represents,  and  the  sum  of  the  products  is  divided  by 
the  total  number  of  tests  of  the  electric  detonator  considered. 

Percentages  of  detonations  in  indirect  tests  of  P.  T.  S.  S.  electric  detonators. 


Class  of  explosive. 

Kind  of  test. 

Grade  of  electric  detonator. 

No.  3. 

No.  4. 

No.  5. 

No.  6. 

No.  7. 

No.  8. 

Percentage 
of  deto- 
nations. 

Number  of 

tests. 

nrcentage 
f  deto- 
tations. 

Number  of 
tests. 

Percentage 
of  deto- 
nations. 

Number  of 

tests. 

Percentage 
of  deto- 
nations. 

"o 

3* 

g  £ 
3"^ 
fc 

Percentage 
of  deto- 
nations. 

"o 

Is 

!« 

fc 

Percentage 
of  deto- 
nations. 

Number  of 
tests. 

Class  1,  subclass  b  .... 

Rate  of  deto- 
nation. 
...do... 

Per 
cent. 
0 

G7 
0 

100 
0 

80 

5 

3 

1 

1 
3 

5 

Per 
cent. 
0 

100 
100 

100 
0 

80 

5 

2 

1 

2 
3 

5 

Per 

cent. 
0 

50 
100 

50 
0 

80 

5 

2 
1 

4 
3 

5 

Per 

cent. 
40 

100 
100 

67 
0 

100 

5 

2 
1 

3 
3 

5 

Per 
cent. 
100 

100 
100 

100 
67 

100 

5 

2 

1 

3 
3 

5 

Per 

cent. 
100 

100 
100 

100 

67 

100 

5 

2 
1 

4 
3 

5 

Class  1  ,  subclass  a,  

40  per  cent  strength  gela- 
tin dynamite  (frozen). 
35  per  cent  strength  gela- 
tin    dynamite     (two 
years  old). 
20  per  cent  "straight" 
mtroglycerin     d  y  n  a  - 
mite  (containing  '6  per 
cent  of  added  water 
and  frozen). 
40  per  cent  strength  gela- 
tin dynamite  (frozen). 

Total  number  of  tests 
Average  percentage 
of  detonations. 

..  do  . 

do  

Small    lead 
block. 

do  

~38.9 

18 

50."  6 

18 

40.6 

20 

63.2 

19 

94.7 

19 

95."  6" 

20 

COMPARATIVE  EXPLOSIVE  EFFICIENCY. 

The  percentages  of  explosive  efficiency  of  the  different  types  of 
P.  T.  S.  S.  electric  detonators  were  obtained  by  averaging  all  tests 
in  which  the  rate  of  detonation  or  compression  was  determined  for  all 
the  electric  detonators.  The  percentages  of  the  individual  electric 
detonators  were  also  averaged,  each  average  percentage  having  a 
value  proportional  to  the  number  of  tests  from  which  computed; 
that  is,  each  percentage  is  multiplied  by  the  number  of  tests  it 
represents,  and  the  sum  of  the  products  is  divided  by  the  total 
number  of  tests  of  the  electric  detonator  considered.  In  each  case 
the  percentage  of  explosive  efficiency  of  the  No.  6  electric  detonator 
is  assigned  a  value  of  100  and  is  used  as  the  unit  of  comparison. 


INDIRECT  TESTS  OF  P.   T.   S.   S.   ELECTRIC   DETONATORS. 


45 


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Class  and  grade  of  explo- 
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Average  

Total  number  of  tests 

II 


46        INVESTIGATIONS  OF  DETONATOKS  AND  ELECTRIC   DETONATORS. 


COMPARATIVE  EXPLOSIVE  EFFICIENCY  OF  P.  T.   S.   S.  ELECTRIC 

DETONATORS. 

The  tabulation  below  shows  the  comparative  explosive  efficiency 
(fig.  3)  of  the  six  grades  of  P.  T.  S.  S.  electric  detonators: 


GRADE  OF 
ELECTRIC 
DETONATOR  PROBABILITY  OF  DETONATION 


EXPLOSIVE  EFFICIENCY 


PER  CENT 

10    to    90    40    BO    60    70    80    90 


No.  3 
No.  4 
No.  6 
No.  6 
No.  7 
No.  8 

FIGURE  3.— Comparative  explosive  efficiency  of  six  grades  of  P.  T.  S.  S. 
electric  detonators  as  determined  by  indirect  tests. 

Comparative  explosive  efficiency  of  six  grades  of  P.  T.  S.  S.  electric  detonators. 


Explosive 

Probabil- 

efficiency 
for  those 

Grade  of  electric  detonator. 

ity  of 

tests  in 

detonation. 

which 

detonation 

occurred. 

Per  cent. 

Per  cent. 

No.  3... 

38  9 

92  1 

No.  4  

50  0 

89  6 

No.5... 

40  0 

89  4 

No.  6  

63  2 

100  0 

No.  7... 

94  7 

100  0 

No.  8  

95  0 

104  5 

TESTS     OF    FOUR     NO.     6    ELECTRIC     DETONATORS     OF 
DIFFERENT   MAKES. 

In  the  tests  of  P.  T.  S.  S.  electric  detonators  as  described  above  the 
composition  of  the  fulminating  charge  was  practically  the  same  in 
each  electric  detonator,  although  there  was  variation  in  the  weight 
of  the  charge.  In  the  tests,  the  results  of  which  are  tabulated  below, 
four  No.  6  electric  detonators  manufactured  by  different  makers 
were  used.  The  weight  of  charge  of  each  of  the  No.  6  electric  deto- 
nators tested  was  approximately  1  gram,  but  each  electric  detonator 
had  a  different  composition.  The  electric  detonators  were  repre- 
sentative of  all  electric  detonators  used  in  the  United  States,  and 
the  tests  made  are  of  especial  importance  for  the  reason  that  they 
established  for  each  electric  detonator  the  charge  equivalent  to  the 
Pittsburgh  testing  station  standard  electric  detonators. 


TESTS   OF   FOUR   NO.    6   ELECTRIC   DETONATORS. 
PHYSICAL  EXAMINATION. 


47 


A  physical  examination  was  made  of  each  of  the  four  electric  deto- 
nators (fig.  4),  the  results  being  given  in  the  following  tabulation. 
Each  item  represents  an  average  of  measurement  of  five  electric 
detonators. 


Special 


Western 
Coast 

SCALE  IN  INCHES. 
1 


Standard 


LEGEND 
Sulphur. 

jAsphaltic  composition. 
fc££^l  Loose  mercury  fulminate. 

|  Picric  acid  and  chlorate  of  potash 
FIGURE  4.— Cross-sectional  view  of  four  No.  6  electric  detonators  of  different  makes. 

Results  of  physical  examination  of  four  No.  6  electric  detonators  of  different  makes. 


WilJM Sulphur  plug. 
iv^iAJj  Loose  gun  cotton. 

I  Compressed  mercury 
fulminate  composition. 


Kind  of  electric  detonator. 


•a  a 

-o-a 


ti 


o>      c. 

O        u 
fit?  ^ 


Vestern  Coast 

Special 

P.T.S.S 

Foreign 


In. 
1.55 
1.75 
1.55 
1.55 


In. 

0.274 
.234 
.274 
.274 


In. 

0.260 
.220 
.260 
.260 


In. 
0.007 
.007 
.007 
.007 


In. 

0.62 
.56 
.28 
.44 


In. 
0.23 
.39 
.27 
.21 


In. 

0.25 
.25 
.25 
.25 


In. 

o.'so 


0.45 
.30 
.25 
.65 


In. 

0.16 
.16 
.12 
.16 


In. 

0.19 
.16 
.94 
.19 


WEIGHT  AND  COMPOSITION  OF  CHARGES. 

Following  is  a  tabulation  presenting  the  weight  of  the  charges  and 
their  chemical  composition  as  determined  by  analysis: 
78875°— Bull.  59—13 4 


INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


' 


Si 


III! 


i 

35 


la 


fsj 

£•33 


til 

£•0     ' 


•ai 
*** 


•^(N  i-i  oo  eo 


Western 
SpeciaU 
P.  T.  S. 
Foreign 


TESTS  OF   FOUE  NO.   6  ELECTRIC  DETONATORS. 
RESULTS  OF  CALORIMETER  TESTS. 


49 


The  results  of  calorimeter  tests  of  the  four  kinds  of  No.  6  electric 
detonator  are  tabulated  below. 

Results  of  calorimeter  tests  of  four  No.  6  electric  detonators. 


Average  heat 

evolved  per  elec- 

tric detonator 

had    each  con- 

Kind of  electric  detonator. 

Number  of 
electric  de- 
tonators 
used  in 
each  test. 

Number  of 
tests  aver- 
aged. 

Average 
heat 
evolved 
per  electric 
detonator. 

Total 
charge  per 
electric  de- 
tonator. 

tained  the  same 
weightofacharge 
consisting  of  77,  7 
per  cent  of  mer- 
cury   fulminate 

and  22.3  per  cent 

of  chlorate  of  pot- 

ash (exact  com- 

bustion).* 

Large 

calones. 

Grams. 

Large  calories. 

Western  Coast  

15 

2 

60.95 

0.8682 

0.61 

Special 

15 

2 

.75 

.9283 

.66 

P.T.S.S  

15 

2 

.62 

.9995 

.71 

Foreign 

15 

3 

cl.12 

1.1748 

.83 

c  Berthelot,  M..  Explosives  and  their  power,  1892,  p.  470. 

&  This  unusually  high  value  is  partly  due  to  the  high  heat  of  total  combustion  of  nitrocellulose  (about 
three  times  that  of  mercury  fulminate). 

c  This  unusually  high  value  is  partly  due  to  the  high  heat  of  total  combustion  of  picric  acid  (about  four 
times  that  of  mercury  fulminate). 

SQUIRTED  LEAD  BLOCK  TESTS. 
The  results  of  the  squirted  lead  block  tests  are  given  herewith. 

Results  of  squirted  lead  block  testsa  of  four  No.  6  electric  detonators. 


Kind  of  electric  detonator. 

Test  No. 

Volume  of  bore  hole. 

Increase  of 
volume. 

Average 
increase 
of  volume. 

Weight  of 
total 
charge. 

Before  test. 

After  test. 

Western  Coast 

/        AA14 
\        AA15 

/        AA  9 
\        AA41 

f        AA10 
\        A  All 

f        AA12 
\        AA26 

C.c. 
1.7 
1.7 

1.4 
1.5 

1.7 
1.7 

1.7 

1.7 

C.c. 
27.7 
28.7 

20.6 
19.3 

20.0 
19.8 

28.9 
28.6 

C.c. 

26.0 
27.0 

19.2 
18.8 

18.3 
18.1 

27.2 
26.9 

C.c. 
}          26.5 

}           19.0 
}           18.2 
}           27.0 

Grams. 
0.8682 

.9283 
.9996 
1.1748 

Special  

P.T.S.S  

Foreign  ...  . 

For  a  description  of  the  procedure  in  these  tests,  see  p.  20. 


50       INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 
CAST  LEAD  BLOCK  TESTS. 

Following  are  tabulated  the  results  (PI.  VI)  of  cast  lead  block  tests 
of  the  four  kinds  of  No.  6  electric  detonators : 

Results  of  cast  lead  block  tests  of  four  No.  6  electric  detonators. 


Kind  of  electric  detonator. 

Test  No. 

Volume  of  bore  hole. 

Increase  of 
volume. 

Average 
increase 
of  volume. 

Weight  of 
total 
charge. 

Before  test. 

After  test. 

Western  Coast 

/        AA  6 
\        AA31 

/        AA33 
\        AA58 

/        AA30 
\        AA55 

/         AA  5 
\        AA54 

C.  c. 
1.8 

1.7 

1.4 
1.4 

1.7 

1.6 

1.7 
1.7 

C.c. 
22.7 
23.2 

16.1 
15.2 

16.0 
15.2 

19.7 
20.0 

C.c. 
20.9 
21.5 

14.7 
13.8 

14.3 
13.6 

18.0 
18.3 

C.c. 
\           21.2 

J           14.2 
14.0 

18.2 

Grams. 
0.8682 

.9283 
.9995 
1.1748 

Special  

P.  T.  S.  S 

Foreign 

TESTS  WITH  LEAD  PLATES. 

Two  series  of  tests  of  the  four  No.  6  electric  detonators  were  made 
by  the  use  of  ^-inch  lead  plates.  In  one  series  the  electric  detonators 
were  placed  on  end  on  the  plates  and  were  detonated,  the  resultant 
depression  of  the  plates  being  recorded.  In  the  other  series  each 
electric  detonator  was  placed  on  its  side  on  the  lead  plate  before  deto- 
nation. 

DETONATORS    ON    END. 

The  results  of  the  lead-plate  tests  in  which  the  detonators  were 
placed  on  end  (PL  VII)  are  tabulated  below: 

Results  of  lead-plate  tests  of  four  No.  6  electric  detonators,  detonators  being  placed  on  end. 


Kind  of  electric  detonator. 

Test  No. 

Volume  of 
water  con- 
tained in 
depression. 

Diameter  of 
crater. 

Depth  of 
crater. 

Height  of 
cone  on 
bottom. 

Western  Coast 

Ml  55 

C.c. 
0  15 

Mm. 
11 

Mm. 
5 

Mm. 
Slight 

Special  

Ml  59 

.25 

11 

6 

2 

P  T  S.S. 

Ml  49 

40 

13 

7 

3 

Foreign  

M153 

.45 

13 

7 

3 

Results  of  lead-plate  tests  of  four  grades  of  electric  detonators,  detonators  being  placed  on 

side. 


Kind  of  electric  detonator. 

Test  No. 

Volume  of 
water  con- 
tained in 
depression. 

Diameter 
of  crater. 

Depth  of 
crater. 

Height  of 
cone  on 
bottom. 

Western  Coast 

M156 

0  45 

26 

12 

4 

Special  

M160 

.50 

19 

11 

4 

P.  T.  S.  S 

a  M150 

50 

21 

13 

5 

Foreign 

M154 

50 

22 

13 

5 

a  Bottom  of  plate  slightly  raised;  not  raised  in  other  tests. 


BUREAU    OF    MINES 


BULLETIN    59      PLATE  VII 


WESTERN  COAST. 


SPECIAL. 


i      *    *     •*      ' 


P.  T.  S.  S.  FOREIGN 

SCORING  OF  LEAD  PLATES  BY  FOUR  NO.  6  ELECTRIC  DETONATORS  PLACED  ON   END. 


TESTS   OF   FOUR   NO.   6  ELECTRIC   DETONATORS. 


51 


DETONATORS    ON    SIDE. 

Following  are  tabulated  the  results  when  the  detonators  were  placed 
on  their  side  (PL  V,  (7)  on  the  lead  plates  before  detonation: 

A  second  series  of  tests  with  the  J-inch  lead  plates,  the  electric 
detonators  being  fired  on  their  side,  was  made,  and  the  resultant  de- 
pressions of  the  plates  were  measured  with  sand.  The  results  are 
tabulated  below: 

Depression  of^-inch  lead  plates  when  electric  detonators  were  fired  on  their  side,  depression 

measured  with  sand. 


Kind  of  electric 
detonator. 

Test  No. 

Plate 
No. 

Weight  of  sand  contained  in  depression, 
measurement  No.— 

Av«r      Grand 

aS        aver' 
age-        age. 

Vol- 
ume.a 

1 

2 

3 

4 

5 

Western  Coast  
Special       .        .  . 

M307 
M307 
M301 
M307 

1 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 
3 

Grams. 
0.535 
.591 
.476 

.507 
.551 
.540 

.574 
.580 
.622 

.635 
.602 
.580 

Grams. 
0.565 
.601 
.470 

.557 
.563 
.536 

.565 
.586 
.600 

.668 
.584 
.560 

Grams. 
0.544 
.602 
.489 

.562 
.566 
.568 

.620 
.607 
.615 

.678 
.594 
.540 

Grams. 
0.551 
.560 
.472 

.540 
.573 
.542 

.620 
.569 
.601 

.684 
.587 
.511 

Grams. 
0.553 
.602 

.485 

.587 
.590 
.551 

.590 
.596 
.598 

.573 
.610 
.520 

Grams.   Grams. 
0.550  \) 
.591  \\  0.540 
.478  J 

.551    1 
.569    }•    .556 
.547   f 

.594  \] 
.588    V    .596 
.607    1 

.  648   1 
.595  \\    .595 
.542   j 

C.  c. 
0.380 

.392 
.420 
.419 

P.T.  S.  S  

Foreign 

a  The  volume  was  computed  from  the  grand  average  by  dividing  this  by  the  specific  gravity  of  the  sand- 
in  this  case  1.42. 

The  results  of  the  tests  are  fairly  satisfactory,  as  they  practically 
agree  with  the  explosive  efficiency  established  for  electric  detonators 
by  the  indirect  methods. 

NAIL  TESTS. 

The  nail  tests  previously  described  were  also  used  in  connection 
with  the  investigation  of  the  four  grades  of  No.  6  electric  detonators. 
The  results  (PL  IV,  B)  are  tabulated  below: 

Results  of  nail  tests  of  four  No.  6  electric  detonators. 


Kind  of  electric  detonator. 

Test  No. 

Angle  of  bending  resulting 
from  trial  No.— 

Average. 

Minimum. 

1 

2 

3 

4 

5 

Western  Coast... 

M286 

M287 
M288 
M300 

24.2 
21.4 
24.4 
20.6 

20 
16 
23 
17 

22 
16 
23 

17 

24 
35 
24 
31 

20 
17 
25 

18 

28 
16 
24 

19 

27 
23 
26 

18 

Special  

P.  T.  S.  S 

Foreign 

52        INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC   DETONATORS.  . 


RATE-OF-DETONATION  TESTS. 

Rate-of-detonation  tests  similar  to  those  with,  the  different  grades 
of  P.  T.  S.  S.  electric  detonators  were  conducted  with  the  four  No.  6 
electric  detonators.  The  results,  according  to  the  explosive  used,  are 
presented  below. 

TESTS  WITH  AN  EXPLOSIVE  OF  CLASS  1,  SUBCLASS  «. 

Following  are  the  results  of  tests  with  an  explosive  of  class  1,  sub- 
class a  (an  ammonium-nitrate  explosive  containing  a  sensitizer  that 
is  itself  a  sensitizer) .  The  diameter  of  the  cartridges  used  was  seven- 
eighths  of  an  inch. 

Results  of  rate-of -detonation  tests  with  an  explosive  of  class  1,  subclass  a. 


Kind  of  electric  detonator. 

Test 
No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Indi-      Aver- 
vidual      age 
rate.       rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Western  Coast  

f  D970 
\  D971 

{D976 
D978 
D979 

j  D966 
\  D967 

/  D974 
i  D973 

Meters    Meters 
per         per 
second,   second. 
2,343  1  2  o,  n 
2,295  /  2'319 

1,891   1 
2,419  \\  2,234 
2,393   J 

2,445  \  o  4,3 
2,472  /  Z'45* 

2,778  X  o  4^ 
2,143  ||  2>46C 

Meters 
per 
second. 
f  2,295 
\  2,250 

(2,296 
2,393 
2,206 

f  2,678 
\  2,586 

/  1,814 
\  2,393 

Meters 
per 
second. 

J  2,272 
I  2,298 

|  2,632 
}  2,104 

Meters 
per 
second. 
I  2,585 
\  2,556 

{2,761 
2,459 
2,419 

(  2,205 
\  2,205 

/  2,795 
\  2,866 

Meters 
per 
second. 

}  2,570 
I  2,546 

}  2,205 
}  2,830 

Meters 
per 
second. 
1  2,445 
1  2,406 

(  2,368 
\  2,432 
(  2,356 

f  2,368 
\  2,356 

/  2,459 
\  2,528 

Meters 
per 
second. 

j-    2,426 
1    2,385 

)•    2,362 
}•    2,494 

Special     . 

P.T.S.  S  

Foreign  

Grand  average  

2,393 

2,326 

2,538 

2,417 

The  average  rate  for  the  meter  length  was  practically  uniform,  but 
such  difference  as  was  shown  indicated  that  the  ascending  order  of 
explosive  efficiency  of  the  detonators  is  as  follows:  P.  T.  S.  S.,  spe- 
cial, Western  Coast,  foreign. 

The  percentage  of  complete  detonations  with  each  detonator  was 
as  follows: 

Percentage  of  complete  detonations  with  an  explosive  of  class  1,  subclass  a. 


Number  of 

Kind  of  electric  detonator. 

Number  of 

tests. 

tests  in 
which  in- 
complete 
detonation 

Percentage 
of  com- 
plete de- 
tonations. 

occurred. 

Per  cent. 

Western  Coast 

2 

0 

100 

Special 

5 

0 

100 

P.  T.  S.S  

2 

o 

100 

Foreign 

3 

1 

67 

TESTS  OF  FOUR  NO.  6  ELECTRIC  DETONATORS. 


TESTS  WITH  AN  EXPLOSIVE  OF  CLASS  1,  SUBCLASS  &. 

Two  rate-of-detonation  tests  were  made  of  each  of  the  four  kinds 
of  No.  6  electric  detonators  on  an  explosive  of  class  1,  subclass  6  (an 
ammonium-nitrate  explosive  containing  a  sensitizer  that  is  not  itself 
an  explosive)  being  used.  The  cartridges  used  were  If  inches  in 
diameter.  In  no  test  did  detonation  occur,  so  that  the  tests  failed 
to  discriminate  between  the  different  kinds  of  electric  detonators. 

TESTS   WITH  A   20  PER   CENT   " STRAIGHT"    NITROGLYCERIN    DYNAMITE. 

The  results  of  tests  with  a  20  per  cent  " straight"  nitroglycerin 
dynamite  are  presented  below.  The  diameter  of  the  cartridges  was 
seven-eighths  of  an  inch. 

Results  of  rate-of-detonation  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite. 


Kind  of  electric  detonator. 

Test 
No. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Western  Coast  

/  D996 
\  D997 

t  D998 
\  D999 

(D1000 
\D1002 

/  D994 
\  D995 

Meters 
per 
second. 
2,778 
3,462 

3,048 
3,299 

3,729 
3,947 

2,922 
3,000 

Meters 
per 
second. 

}  3,120 
}  3,174 
}  3,838 
}  2,961 

Meters 
per 
second. 
I  2,960 
I  2,679 

/  2,928 
\  2,587 

(  2,683 
\  2,443 

/  3,125 
\  2,557 

Meters 
per 
second. 

j-2,820 
}  2,758 
}  2,563 
}2,841 

Meters 
per 
second. 
I  3,147 
\  3,285 

/  3,069 
\  3,027 

/  2,767 
\  3,309 

/  2,866 
\  3,061 

Meters 
per 
second. 

}  3,216 
|  3,048 
}  3,038 
}  2,964 

Meters 
per 
second. 
/  3,000 
I  3,147 

/  3,027 
\  2,967 

f  2,933 
\3,158 

/  2,941 
\  2,903 

Meters 
per 
second. 

}    3,074 
}•    2,997 
}•    3,046 
[    2,922 

Special 

P.  T.  S  S 

Foreign  

Grand  average 

3,273 

2,746 

3,066 

3,010 

The  figures  representing  the  grand  averages  indicate  that  the  rate 
was  influenced  by  a  negative  acceleration  in  the  second  quarter  meter 
followed  by  a  positive  acceleration  in  the  second  half  meter.  This 
acceleration  occurred  in  all  tests  except  D996  and  D994. 

The  uniformity  of  the  rates  for  the  last  half  meter  and  the  meter  is 
noteworthy. 

With  a  20  per  cent  "straight "  nitroglycerin  dynamite  such  difference 
as  was  shown  in  the  tests  indicated  that  the  ascending  order  of  ex- 
plosive efficiency  is:  Foreign,  special,  P.  T.  S.  S.,  Western  Coast. 

TESTS    WITH    A     40    PER    CENT    STRENGTH    AMMONIA    DYNAMITE    CON- 
TAINING  NITROSUBSTITUTION   COMPOUNDS. 

Following  are  tabulated  the  results  of  tests  with  a  40  per  cent 
ammonia  dynamite  containing  nitrosubstitution  compounds.  The 
explosive  was  repacked  in  cartridges  seven-eighths  of  an  inch  in 
diameter. 


54       INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


Results  of  rate-of-detonation  tests  with  a  40  per  cent  strength  ammonia  dynamite  contain- 
ing nitrosubstitution  compounds. 


Kind  of  electric  detonator. 

Test 
Xo. 

Rate  of  detonation  in  tube. 

First  quarter. 

Second  quarter. 

Second  half. 

Full  length. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Indi- 
vidual 
rate. 

Aver- 
age 
rate. 

Western  coast  

Special... 

/D913 
\D923 

f  D879 
\D914 

[D904 
\  D919 
ID920 

/D912 
\D922 

Meters 
per 
second. 
2,557 
3,082 

2,820 
2,587 

2,368 
2,472 
2,250 

2,250 
2,616 

Meters 
per 
second. 

\  2,820 
}  2,704 

t  2,363 
|  2,  433 

Meters 
per 
second. 
/  2,394 
\  2,500 

/  2,588 
\  2,781 

(2,296 
3,041 
2,446 

/  3,129 
\  3,125 

Meters 
per 
second. 

}  2,447 
j-  2,684 

I  2,594 
}  3,  127 

Meters 
per 
second, 
i  2,812 
\  2,  616 

J  2,900 
\  3,048 

f  2,572 
\  2,663 
I  2,543 

/  2,446 
\  2,557 

Meters 
per 
second. 

}  2,714 
\  2,974 

I  2,593 
j-  2,502 

Meters 
per 
second. 
(  2,632 
\2,687 

/  2,794 
\  2,853 

|  2,446 
\  2,695 
I  2,439 

/  2,528 
\  2,  542 

Meters 
per 
second. 

|    2,660 
\    2,824 

1    2,527 
j    2,535 

P.  T.  S.  S 

Foreign  

The  rate  for  the  second  quarter  meter  was  the  highest  for  the 
P.  T.  S.  S.  and  the  foreign  electric  detonators. 

With  a  '40  per  cent  strength  ammonia  dynamite  containing  nitro- 
substitution compounds  the  tests  indicated  that  the  ascending  order 
of  explosive  efficiency  is:  P.  T.  S.  S.,  foreign,  Western  Coast,  special. 

TESTS  WITH  A  35  PEE  CENT  STRENGTH  GELATIN  DYNAMITE  2  YEARS  OLD. 

The  results  of  tests  with  a  35  per  cent  strength  gelatin  dynamite 
(two  years  old)  are  tabulated  below.  The  diameter  of  the  cartridges 
used  was  1J  inches. 

Results  of  rate-of-detonation  tests  with  a  35  per  cent  strength  gelatin  dynamite  two  years  old. 


Kind  of  electric  detonator. 

Test  No. 

Length  a 
of  part  of 
file  blown 
off  or  de- 
tonated. 

Percent- 
age of  file 
that  de- 
tonated. 

Average. 

Remarks. 

Western  Coast  

(     D897 

Inches. 
7.0 

Per  cent. 
17 

Per  cent. 
\       18.0 

/Partial  detonation. 

Special                                           

\     D898 
/     D901 

8.0 
10.0 

19 
24 

J 

\       22.5 

\        Do. 
f        Do. 

P  T  S  S 

\     D902 

(     D889 
•I      D896 

9.0 

7.0 
18.0 

21 

0 
43 

/ 
J27.5 

\        Do. 

[No  detonation. 
<  Partial  detonation 

Foreign  

I     D958 
/     D899 

17.0 
6.0 

40 
14 

. 
>        15.5 

1       Do. 
/       Do- 

\     D900 

7.0 

17 

/ 

\       Do. 

o  Full  length  of  file,  42  inches. 

The  evidence  of  no  detonation  in  test  D889  was  that  nothing  but 
the  noise  of  the  electric  detonator  was  audible  when  the  trial  was 
made. 


TESTS  OF  FOUR  NO.  6  ELECTRIC  DETONATORS. 


55 


With  the  two-year-old  sample  of  35  per  cent  strength  gelatin 
dynamite  used  the  tests  indicated  that  the  ascending  order  of  ex- 
plosive efficiency  is:  Foreign,  Western  Coast,  special,  P.  T.  S.  S. 

The  percentage  of  partial  detonations  with  each  electric  detonator 
was  as  follows: 

Percentage  of  partial  detonations  with  a  85  per  cent  strength  gelatin  dynamite  two  years  old. 


Kind  of  electric  detonator. 

Number  of 
tests. 

Number  of 
tests  in 
which  partial 
detonation 
occurred. 

Percentage 
of  complete 
detona- 
tions. 

Western  Coast 

2 

2 

Per  cent. 
100 

Special  

2 

2 

100 

P.  T.  S.  S 

3 

2 

67 

Foreign  

2 

2 

100 

TESTS   WITH  A  40  PER    CENT    STRENGTH    GELATIN    DYNAMITE,    FROZEN. 

Following  are  the  results  of  tests  with  a  40  per  cent  strength 
gelatin  dynamite  (frozen).  The  diameter  of  the  cartridges  used  was 
1J  inches. 

Results  of  rate-of-detonation  tests  with  a  40  per  cent  strength  gelatin  dynamite,  frozen. 


Kind  of  electric  detonator. 

Test  No. 

Rate  of  detonation  in  tube. 

First 
quarter. 

Second 
quarter. 

Second 
half. 

Full 
length. 

"Western  Coast 

D1091 
D1092 
D1093 
D1090 

Meters 
per 
second. 
3,273 
4,167 
4.167 
3,090 

Meters 
per 
second. 
7,177 
6,357 
7,759 
14,833 

Meters 
per 
second. 
5,705 
6,013 
6,522 
5,361 

Meters 
per 
second. 
5,028 
5,460 
5,921 
5,235 

Special 

P.  T.  S.  S  

Foreign 

Grand  average 

3,674 

9,032 

5,900 

5,411 

The  figures  included  in  the  "  grand  average "  show  that  the  maxi- 
mum, rate  occurred  in  the  second  quarter,  with  a  subsequent  falling 
off  in  the  rate;  moreover,  the  rate  varied  similarly  in  each  individual 
test. 

With  the  explosive  used  in  the  tests  the  results  indicate  that  the 
ascending  order  of  explosive  efficiency  is:  Western  Coast,  foreign, 
special,  P.  T,  S.  S. 

TESTS  WITH  A  35  PER  CENT  STRENGTH  GELATIN  DYNAMITE  3  YEARS  OLD. 

One  test  each  of  the  Western  Coast,  the  special,  and  the  foreign 
No.  6  electric  detonators  was  made  with  a  35  per  cent  strength  gela- 
tine dynamite  3  years  old.  The  diameter  of  the  cartridges  used  was 
1J  inches.  No  detonation  took  place  in  any  of  the  tests,  as  the 
explosive  was  so  old  and  insensitive  to  detonation  that  for  the  pur- 
pose of  discriminating  between  detonators  it  was  useless. 


56       INVESTIGATIONS  OF  DETONATOES  AND  ELECTRIC  DETONATORS. 
SMALL  LEAD  BLOCK  TESTS. 

Small  lead  block  tests  were  made  with  the  four  No.  6  electric 
detonators.  The  results,  according  to  the  explosive  tested,  are  given 
below. 

TESTS   WITH  A  20  PER    CENT   "  STRAIGHT"    NITROGLYCERIN    DYNAMITE. 

Three  series  of  tests  were  conducted  with  a  20  per  cent  " straight" 
nitroglycerin  dynamite  in  different  conditions  as  indicated  below. 

Results  of  small  lead  block  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite  with 

6  per  cent  of  added  water. 


Kind  of  electric  detonator. 

Test  No. 

Compres- 
sion. 

Average 
compres- 
sion. 

Western  Coast  

(          B759 
\          B768 

Mm. 
15.00 
14.75 

Mm. 
115.00 

Special 

I          B777 

|          B760 
•1          B769 

15.25 

14.00 
15  25 

I            14  83 

P.  T.  S.  S 

I         B778 

|          B761 
•!          B770 

15.25 

15.00 
15.00 

I 

115  00 

Foreign  

I          B779 

|          B758 
\          B767 

15.00 

14.25 
14.75 

(14.67 

I          B776 

15.00 

In  the  tests  the  explosive  produced  nearly  uniform  individual  com- 
pressions and  little  difference  in  the  average  compressions,  but  such 
difference  as  was  shown  indicated  that  the  ascending  order  of  explosive 
efficiency  is:  Foreign,  special,  Western  Coast,  P.  T.  S.  S. 

The  results  of  tests  with  the  same  explosive,  but  containing  4  per 
cent  of  added  water  and  frozen,  were  as  follows : 

Results  of  small  lead-block  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite  con- 
taining 4  per  cent  of  added  water  and  frozen. 


Kind  of  electric  detonator. 

Test 
No. 

Tempera- 
ture of 
frozen 
explosive. 

Percentage 
of  water 
added. 

Compres- 
sion. 

Average 
compres- 
sion. 

Western  Coast... 

B651 

°<7. 
-9.0 

4.0 

Mm. 
12.75 

Mm. 
12.75 

Special  

B652 

—9.0 

4.0 

12.50 

12.50 

P  T  S  S 

B653 

—9.0 

4.0 

13  00 

13.00 

Foreign  

B650 

—9.0 

4.0 

12.75 

12.  75 

With  the  explosive  in  the  condition  mentioned,  the  results  of  the 
tests  indicate  that  the  ascending  order  of  explosive  efficiency  is: 
Special,  Western  Coast,  foreign,  and  P.  T.  S.  S. 

Further  tests  were  conducted  with  6  per  cent  of  water  added  to 
the  explosive  and  the  explosive  frozen  (temperature  9°  C.)-  Three 
tests  were  made  with  each  of  the  four  grades  of  electric  detonators, 
but  the  explosive  was  too  insensitive  to  detonation  to  be  discrimi- 
native, as  no  compression  of  any  of  the  blocks  was  produced. 


TESTS  OF  FOUR  NO.  6  ELECTRIC  DETONATORS. 


57 


TESTS    WITH   A   40   PER   CENT    STRENGTH   AMMONIA   DYNAMITE. 

Following  are  the  results  of  tests  with  a  40  per  cent  ammonia 
dynamite,  to  which  had  been  added  6  per  cent  of  water: 

Results  of  small  lead  block  tests  with  a  40  per  cent  strength  ammonia  dynamite  containing 

6  per  cent  of  added  water. 


Kind  of  electric  detonator. 

Test  No. 

"H-IF 

Western  Coast                            

B660 

Mm.             Mm. 
8.25   I 

Special                                               -         

B669 
B678 
B687 
B696 

B661 

9.00 
9.00    I            8.75 
8.00 
9.50  J 

8.00  1 

p  T  S  S                 ,  

B670 
B679 
B688 
B697 

B662 

8.25 
8.50  1}             8.40 
7.75 
9.25   J 

9.75 

B671 
B680 
B689 
B698 

B659 

8.75 
9.25                 8.95 
7.75 
9.25 

8.00   | 

B668 
B677 
B686 
B695 

10.00 
9.25    ^             9.20 
9.50 
9.25   J 

The  results  were  obviously  erratic.  However,  the  tests  indicated 
that  the  ascending  order  of  explosive  efficiency  is:  Special,  Western 
Coast,  P.  T.  S.  S.,  foreign. 

TESTS   WITH   A   40    PER   CENT   STRENGTH   GELATIN   DYNAMITE,  FROZEN. 

The  results  of  tests  with  a  40  per  cent  strength  gelatin  dynamite 
(frozen)  were  as  follows  (PL  V,  B) : 
Results  of  small  lead  block  tests  with  a  40  per  cent  strength  gelatin  dynamite,  frozen. 


Kind  of  electric  detonator. 

Test 
No. 

Tempera- 
ture of 
frozen 
explosive. 

Compres- 
sion. 

Average 
compres- 
sion. 

Western  Coast                           

B635 

°C. 
-2.5 

Mm. 
14.75 

Mm. 

Special 

B642 
B705 
B714 
B723 

B636 

-5.0 
+  .5 
+2.5 
+2.5 

-2.5 

17.75 
12.50 
12.50 
12.00 

12.75 

13.90 

P  T  S  S 

B643 
B706 
B715 
B724 

B631 

-5.0 
+  .5 
+2.5 
+2.5 

-4.5 

18.00 
15.00 
14.75 
13.75 

12.50 

14.85 

B644 
B707 
B716 
B725 

B634 

-5.0 
+  -5 
+2.5 
+2.5 

-2.5 

19.25 
14.25 
14.25 
14.50 

11.00 

14.95 

B641 
B704 
B713 
B722 

-5.0 
+  .5 
+2.5 
+2.5 

18.00 
15.00 
16.25 
15.50 

I           15.  15 

58    INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


As  indicated  by  the  table,  the  results  of  the  tests  were  very  erratic 
with  this  frozen  gelatin  dynamite.  The  insensitiveness  of  this  explo- 
sive has  been  mentioned  in  a  foregoing  section  regarding  the  incom- 
pleteness of  detonation  in  tests  with  the  Nos.  3,  4,  and  5  electric  deto- 
nators. With  the  No.  6  electric  detonators,  however,  detonation  was 
complete  in  every  trial. 

EXPLOSION-BY-INFLUENCE  TESTS. 

Tests  involving  explosion  by  influence  as  outlined  in  a  foregoing 
section  relative  to  tests  of  different  grades  of  P.  T.  S.  S.  electric  deto- 
nators were  made  of  the  four  kinds  of  No.  6  electric  detonators,  as 
described  below: 

TESTS   WITH   AN   EXPLOSIVE    OF   CLASS    1,  SUBCLASS  a. 

Following  are  the  results  of  tests  with  an  explosive  of  class  1,  sub- 
class a  (an  ammonium-nitrate  explosive  containing  a  sensitizer  that 
is  itself  an  explosive).  The  size  of  the  cartridges  used  was  1J  by  8 
inches  and  the  average  weight  was  166  grams. 

Results  of  explosion-by-inftuence  tests  with  an  explosive  of  class  1,  subclass  a  (sample  1). 


Kind  of  electric  detonator. 

Test  No. 

Distance 
separating 
cartridges. 

Result  on  upper 
cartridge. 

Established 
distance  at 
which  deto- 
nation did 
not  occur. 

Western  Coast 

J758 

Inches. 
2 

Did  not  explode.  .  . 

Inches. 

} 

J759 
J760 

1 
2 

Exploded  
Did  not  explode  

\ 

Special 

J761 

1 

Exploded 

P  T  S  S 

J762 
J763 

J741 

2 
2 

4 

Did  not  explode  
do  

do 

2 

J742 

3 

...do... 

J743 

2 

do 

J744 

1 

Exploded  

3 

J745 

2 

do  ... 

J746 

3 

Did  not  explode  

Foreign  

J753 

3 

...do... 

J754 

2 

do  

J755 
J756 
J757 

1 
0 
1 

do  
Exploded  

Did  not  explode 

1 

With  the  ammonium-nitrate  explosive  used,  the  results  of  the  tests 
indicated  that  the  ascending  order  of  explosive  efficiency  is :  Foreign, 
Western  Coast  and  special,  P.  T.  S.  S. 

TESTS    WITH   AN    EXPLOSIVE    OF   CLASS   4, 

The  results  of  tests  with  an  explosive  of  class  4  (an  explosive  in 
which  the  characteristic  material  is  nitroglycerin)  are  tabulated 
below.  The  size  of  the  cartridges  used  was  1J  by  8  inches,  their 
average  weight  being  161  grams,  except  that  in  the  trials  under  test 
J896  the  upper  cartridge  weighed  110  grams  and  was  5  inches  long. 


TESTS   OF   FOUR   NO.   6   ELECTRIC   DETONATORS.  59 

Results  of  explosion-by-inftuence  tests  with  an  explosive  of  class  4- 


Kind  of  electric  detonator. 

Test  No. 

Distance 
separat- 
ing car- 
tridges. 

Result  on  upper 
cartridge. 

Western  Coast      .                

J895 

Inches. 
5 

Exploded. 

Special                           

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 

5 
5 
4 
4 
4 

5 

Did  not  explode. 
Do. 
Do. 
Exploded. 
Do. 
Did  not  explode. 

Exploded. 

p.  T.  S.  S      

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 
5 
5 
4 
4 
4 

5 

Did  not  explode. 
Do. 
Do. 
Exploded. 
Do. 
Did  not  explode. 

Do. 

Foreign                           

J895 
J895 
J895 
J896 
J896 
J896 

J895 

5 
5 
5 
4 

4 
4 

5 

Do. 
Do. 
Exploded. 
Do. 
Do. 
Did  not  explode. 

Do. 

J895 
J895 
J895 
J896 
J896 
J896 

5 
5 
5 
4 
4 
4 

Do. 
Do. 
Do. 
Do. 
Do. 
Do. 

Percentage  of  explosions  of  the  upper  cartridge  in  explosion-by-inftuence  tests  with  an 

explosive  of  class  4. 


Kind  of  electric  detonator. 

Number  of 
tests. 

Number  of 
explosions  of 

cartridge. 

Percentage 
of  explo- 
sions of 
upper 
cartridge. 

Western  Coast                   .  .          

7 

3 

Per  cent. 
43 

Special 

7 

3 

43 

p.  T.  S.  S         

7 

3 

43 

Foreign                                                     

7 

0 

0 

In  all  tests  in  which  the  distance  separating  cartridges  was  5  inches 
the  bottoms  of  the  cartridges  (as  packed)  faced  each  other;  in  all 
tests  in  which  the  distance  was  4  inches  the  tops  of  the  cartridges 
faced  each  other. 

The  tests  indicated  that  the  foreign  electric  detonator  was  not  as 
effective  under  the  conditions  of  the  tests  as  were  the  other  three. 

TESTS  WITH  A  40  PER  CENT   STRENGTH  AMMONIA  DYNAMITE    CONTAIN- 
ING  NITROSUBSTITUTION    COMPOUNDS. 

Following  are  the  results  of  tests  with  a  40  per  cent  strength 
ammonia  dynamite  containing  nitrosubstitution  compounds.  The 
cartridges  used  measured  1J  by  8  inches  and  their  average  weight 
was  226  grams. 


60   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 


Results  of  explosion-by-influence  tests  with  a  40  per  cent  strength  ammonia  dynamite  con- 
taining nitrosubstitution  compounds. 


Kind  of  electric  detonator. 

Test 
No. 

Distance 
separating 
cartridges. 

Result  on  upper 
cartridge. 

Distance 
at  which 
detonation 
did  not 
occur. 

Western  Coast 

J714 

Inches. 
g 

Exploded 

Inches. 

J715 

9 

Did  not  explode  

9 

J716 

9 

do 

[ 

Special 

J717 

g 

do  

J718 

7 

Exploded  

g 

J719 

g 

Did  not  explode.  .  . 

P.  T.  S.  S         .         ... 

J689 

14 

.  do... 

J690 

12 

do 

J691 

g 

do    . 

J692 

7 

do 

J693 

g 

do  

J694 

4 

Exploded  

8 

J695 

5 

do  . 

J696 

6 

..do  

J697 

7 

do 

J698 

g 

Did  not  explode  

J699 

g 

do 

Foreign  

J711 

g 

..  do  

I 

J712 

7 

Exploded 

I                  g 

J713 

g 

Did  not  explode... 

J 

The  tests  show  practically  the  same  result  regardless  of  the  electric 
detonator  used. 

TESTS  WITH  A   35  PER   CENT   STRENGTH   GELATIN    DYNAMITE    2    YEARS 

OLD. 

The  results  of  tests  with  a  35  per  cent  strength  gelatin  dynamite 
(two  years  old)  are  tabulated  below.  The  cartridges  used  were  1 J  by 
8  inches,  their  average  weight  being  265  grams. 

Results  of  explosion-by -influence  tests  with  a  35  per  cent  strength  gelatin  dynamite  (two 

years  old). 


Kind  of  electric  detonator. 

Test 
No. 

Distance 
separating 
cartridges. 

Result  on  upper 
cartridge. 

Western  Coast  

J734 

Inches. 
0 

Did  not  explode. 

Special  

J735 
J737 

0 

o 

Do. 
Do. 

P.  T.  S.  S... 

J738 
J724 

0 
6 

Do. 
Do. 

Foreign 

J725 
J726 
J727 
J728 
J729 

J736 

5 
4 
2 
0 
0 

o 

Do. 
Do. 
Do. 
Do. 
Do. 

Do. 

J739 

0 

Do. 

TESTS  OF  FOUR  NO.  6  ELECTRIC  DETONATORS. 


61 


These  tests  failed  to  discriminate  between  the  different  detonators, 
as  in  no  trial  did  the  explosion  of  the  lower  cartridge  cause  the  detona- 
tion of  the  upper  cartridge. 

TBAUZL  LEAD  BLOCK  TESTS/* 

In  testing  the  four  kinds  of  No.  6  electric  detonators  the  Trauzl 
lead  block  tests  were  used  in  addition  to  the  tests  previously  described. 

The  Trauzl  lead  blocks  are  cylindrical  in  shape,  measuring  200  mm. 
in  diameter  and  200  mm.  in  height.  They  have  an  axial  bore  hole  25 
mm,  in  diameter  and  125  mm.  in  depth.  The  charge  of  20  grams  of 
the  explosive  in  which  the  electric  detonator  was  embedded  was 
placed  in  the  bottom  of  the  bore  hole  and  no  stemming  was  used. 
The  increase  in  the  volume  of  water  that  the  bore  hole  would  contain 
after  an  explosion  was  the  result  recorded. 

Following  is  a  tabulation  of  results  of  Trauzl  lead  block  tests  in 
which  a  20  per  cent  "straight"  nitroglycerin  dynamite  was  used.  The 
charge  of  explosive  in  each  test  was  20  grams,  to  which  was  added 
6  per  cent  of  water. 

Results  of  Trauzl  lead  block  tests  with  a  20  per  cent  "straight"  nitroglycerin  dynamite. 


Kind  of  electric  detonator. 

Test  No. 

Expansion. 

•  Average 
expansion. 

Western  Coast 

i          A817 

C.c. 
175 

C.c. 

Special  

\          A818 
/          A819 

173 
177 

174 

p.  T.  S.  S  

\          A821 
f          A822 

176 

178 

I7B 

Foreign  ... 

V          A824 
/          A815 

175 

178 

171 

\          A816 

179 

178 

As  indicated  by  the  table,  the  average  expansion  of  the  blocks  in 
each  test  was  nearly  the  same. 

PERCENTAGES   OF  DETONATIONS  IN   INDIRECT  TESTS  OF  FOUR 
KINDS  OF  NO.  6  ELECTRIC  DETONATORS. 

The  percentages  of  detonations  in  the  indirect  tests  of  the  four 
kinds  of  No.  6  electric  detonators  are  given  below.  The  percentages 
of  detonations  in  the  tests  of  each  electric  detonator  are  also  aver- 
aged, each  average  percentage  having  a  value  proportional  to  the 
number  of  tests  from  which  it  is  computed;  that  is,  each  percentage  is 
multiplied  by  the  number  of  tests  it  represents  and  the  sum  of  the 
products  is  divided  by  the  total  number  of  tests  of  the  electric  deto- 
nator considered. 


a  For  a  more  extended  description  of  this  test  see  Bull.  15,  Bureau  of  Mines:  Investigations  of  explosives 
used  in  coal  mines;  with  a  chapter  on  the  natural  gas  used  at  Pittsburgh,  by  G.  A.  Burrell,  and  an  intro- 
duction by  C.  E.  Munroe,  by  Clarence  Hall,  W.  O.  Snelling,  and  S.  P.  Howell,  1912,  pp.  114-110, 


62   INVESTIGATIONS  OF  DETONATOKS  AND  ELECTRIC  DETONATORS. 

Percentages  of  detonations  in  indirect  tests  of  four  kinds  of  No.  6  electric  detonators. 


Western  Coast. 

Special. 

P.T.S.S. 

Foreign. 

Class  and  grade  of 
explosive. 

Character  of 
test. 

Per- 

centage 
of  deto- 
nations. 

Num- 
ber of 
tests. 

Per- 
centage 
of  deto- 
nations. 

Num- 
ber of 

tests. 

Per- 
centage 
of  deto- 
nations. 

Num- 
ber of 
tests. 

Per- 
centage 
of  deto- 
nations. 

Num- 
ber of 
tests. 

Per  ct. 

Per  ct. 

Per  ct. 

Per  ct. 

Class    1,    subclass    a 

Rate  of  det- 

100 

2 

100 

5 

100 

2 

67 

3 

(sample  1). 

onation. 

40  per  cent  strength 

do  

100 

1 

100 

1 

100 

1 

100 

1 

gelatin  dynamite 

35  per  cent  strength 
gelatin  dynamite 
(2  years  old). 

do  

100 

2 

100 

2 

67 

3 

100 

2 

20  per  cent  "straight  " 
nitroglycerin   dyna- 
mite (frozen  and  con- 

Small lead 
block. 

0 

3 

0 

3 

0 

3 

0 

3 

taining  6  per  cent  of 

added  water). 

40  per  cent  strength 
gelatin  dynamite 

do  .. 

100 

5 

100 

5 

100 

5 

100 

5 

(frozen). 

55  5 

71.4 

63  2 

61  1 

Total  number  of  tests 

18 

21 

19 

18 

COMPARATIVE  EXPLOSIVE  EFFICIENCY. 

The  percentage  of  explosive  efficiency  of  the  four  kinds  of  No.  6 
electric  detonators  was  obtained  by  averaging  all  tests  in  which  the 
rate  of  detonation,  compression,  or  expansion  was  determined  for  all 
detonators.  Each  percentage  was  given  a  value  proportional  to  the 
number  of  tests  from  which  the  percentage  was  computed.  In  each 
case  the  percentage  of  explosive  efficiency  of  the  P.  T.  S.  S.  No.  6 
electric  detonator  is  given  a  value  of  100  and  is  taken  as  the  unit 
of  comparison. 


TESTS  OF  FOUR  NO.  6  ELECTRIC  DETONATORS. 


63 


Kind  of  electric  detonator. 

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Class  of  explosive. 

20  per  cent  "straight"  nitroglycerin  dynamite  in  |-inch 
cartridges. 
40  per  cent  strength  ammonia  dynamite  (containing  ni- 
trosubstitution  compounds)  in  |-inch  cartridges. 
Class  1,  subclass  a  (sample  1)  in  {-inch  cartridges  
40  per  cent  strength  gelatin  dynamite  (frozen  in  IJ-inch 
cartridges). 
35  per  cent  strength  gelatin  dynamite  (2  years  old)  
20  per  cent  "straight"  nitroglycerin  dynamite  (contain- 
ing 6  per  cent  of  added  water). 
20  per  cent  "straight"  nitroglycerin  dynamite  (contain- 
ing 4  per  cent  of  added  water). 
40  per  cent  strength  gelatin  dynamite  (frozen)  
40  per  cent  strength  ammonia  dynamite  (containing  6 
per  cent  of  added  water). 
20  per  cent  "  straight  "  nitroglycerin  dynamite  (contain- 
ing 6  per  cent  of  added  water). 

Average  

Total  number  of  tests  

5875°— Bull.  59—13- 


64       INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 

COMPARATIVE     EXPLOSIVE     EFFICIENCY     OF     FOUR    KINDS    OF 
NO.  6  ELECTRIC  DETONATORS. 

The  comparative  explosive  efficiency  of  the  four  grades  of  electric 
detonators  (fig.  5),  as  established,  is  tabulated  below. 


GRADE  OF 
ELECTRIC 
DETONATOR  PROBABILITY  OF  DETONATION 


EXPLOSIVE  EFFICIENCY 
PER  CENT 


FIGTJKE  5.— Comparative  explosive  efficiency  of  four  kinds  of  No.  6 
electric  detonators  as  established  by  indirect  tests. 

Explosive  efficiency  of  four  kinds  of  No.  6  electric  detonators. 


Kind  of  electric  detonator. 

Percentage  of 
probability  of 
detonation. 

Explosive 
efficiency  for 
those  tests  in 
which  detona- 
tion occurred. 

Western  Coast.  .      .                                                         

Per  cent. 
65.5 

Per  cent. 
93.5 

Special 

71.4 

95.5 

P.  T.  S.  S.  No.  6...                                                                    

63.2 

100.0 

Foreign  . 

61.1 

95.2 

RELATIVE  STRENGTH  OF  DETONATORS  AND  ELECTRIC 

DETONATORS. 

It  is  generally  recognized  that  the  safest  way  of  firing  shots  in 
blasting  operations  is  with  electric  detonators  by  means  of  the  electric 
current.  This  is  especially  true  in  gaseous  coal  mines,  because  if 
fuse  is  used  the  flame  produced  by  the  burning  fuse  may  ignite 
such  inflammable  gaseous  mixtures  as  are  present.  There  is  also 
danger  of  a  hangfire  when  the  charge  may  be  exploded  unexpectedly, 
due  to  the  smoldering  of  the  fuse. 

There  are,  however,  many  conditions  of  mining  under  which 
electric  detonators  can  not  be  used  advantageously.  In  driving 
drifts  in  many  of  the  metal  mines  of  this  country  fuse  is  generally 
used.  In  work  of  this  kind  it  is  often  necessary  to  fire  dependent 
shots,  and  the  flying  rock  from  one  shot  may  disconnect  or  cause 
short-circuiting  of  the  electric  wires  of  the  detonators  wired  for 
succeeding  shots.  When  fuse  is  used,  different  lengths  can  be  cut 
and,  before  lighting,  the  projecting  ends  can  be  coiled  in  a  place 
within  the  mouth  of  the  hole  where  they  are  wall  protected. 

It  has  been  observed  that  mercury  fulminate  ignited  in  small 
quantities  develops  its  full  force  only  when  confined.  It  also 
has  been  believed  that  the  sulphur  plug  in  an  electric  detonator 


STRENGTH    OF   DETONATORS   AND   ELECTRIC   DETONATORS. 


65 


offers  more  confinement  to  the  fulminating  composition  of  a  detonator 
than  a  piece  of  fuse  does,  even  when  the  fuse  is  properly  used  and 
securely  crimped  in  place.  Therefore  it  ssemed  desirable  to  make 
comparative  efficiency  tests  of  both  electric  detonators  and  detonators 
fitted  with  fuse.  The  nail  test  was  adopted  for  the  reason  that  it 
produced  more  nearly  the  results  established  for  the  efficiency  of 
detonators  than  any  of  the  other  direct  methods. 

The  nail  test  was  made  with  the  No.  3  and  the  No.  6  detonators 
and  with  the  electric  detonators  made  from  these  detonators,  with  the 
following  results: 

Results  of  nail  tests  with  No.  3  and  No.  6  detonators  and  electric  detonators. 


Grade  of  detonator  or  electric  detonator. 

Test 
No. 

Degrees  of  bending 
in  trial— 

Aver- 
age. 

Mini- 
mum. 

1 

2 

3 

4 

5 

M289 
M279 
M318 
M321 

8.2 
9.2 
31.4 
31.6 

7 
7 
29 
27 

8 
12 
32 
31 

7 
10 
29 
31 

9 
8 
35 
33 

9 
9 
30 
36 

8 
7 
31 
27 

No  3  electric  detonator                  

No  6  electric  detonator         

a  Fired  with  fuse  placed  against  the  compressed  charge  of  mercury  fulminate  composition  and  crimped 
in  place. 

The  compressed  charge  of  the  No.  6  electric  detonator  weighed 
1.0225  grams  and  consisted  of  89.61  per  cent  of  mercury  fulminate 
and  10.39  per  cent  of  potassium  chlorate.  The  priming  charge  con- 
sisted of  0.02  gram  of  loose  guncotton.  As  the  weight  of  charge  of 
this  electric  detonator  was  practically  the  same  as  of  the  P.  T.  S.  S. 
electric  detonator,  the  increased  strength  as  shown  by  the  nail  test 
(nail  bent  31.6°  by  the  No.  6  electric  detonator  as  compared  with 
24.4°  by  the  P.  T.  S.  S.  electric  detonator)  would  indicate  that  the 
quantity  of  compressed  charge  in  the  detonator  may  be  a  function  of 
the  efficiency  of  the  detonator. 

The  tests  showed  that  with  low-grade  detonators  the  strength  of 
electric  detonators  is  slightly  greater  than  that  of  the  corresponding 
detonators,  but  that  with  greater  charges,  such  as  the  No.  6  detonators 
contain,  the  strength  of  the  two  types  is  practically  the  same.  This 
indicates  that  the  additional  confinement  given  by  the  plug  of  the 
electric  detonator  as  compared  with  the  fuse  of  the  fuse  detonator  is 
important  only  with  the  low-grade  detonators. 

A  serious  objection  to  the  use  of  fuse  and  detonators  in  wet  blasting 
is  the  fact  that  it  is  impossible  to  perfect  a  waterproof  seal  at  the  top 
of  the  detonator  when  it  is  crimped  on  the  fuse.  The  ordinary  fuse 
crimper  depends  on  flattening  the  sides  of  the  copper  shell  to  con- 
tract the  diameter  of  the  detonator.  Tests  have  shown  that  when  a 
detonator  is  crimped  on  a  fuse  in  this  manner  and  submerged  under 


66   INVESTIGATIONS  OF  DETONATOES  AND  ELECTRIC  DETONATORS. 

water  for  30  minutes  the  fulminating  charge  and  the  powder  train  at 
the  end  of  the  fuse  in  the  detonator  become  damp.  The  spit  of  the 
lighted  fuse,  if  the  fuse  burns  through,  is  usually  of  insufficient  in- 
tensity to  cause  an  explosion  of  the  fulminating  charge.  In  some  cases 
a  sharp  explosion  or  an  explosion  of  a  very  low  order  occurs.  If  only 
a  little  water  enters  the  detonator,  the  spit  of  the  burning  fuse  is 
often  sufficient  to  cause  the  fulminating  charge  to  detonate  with  a 
sharp  report  and  completely  destroy  the  copper  shell.  In  some  of 
the  tests  70  to  80  per  cent  of  the  compressed  fulminating  charge  was 
recovered  in  the  lower  part  of  the  copper  shell.  The  spit  of  the  burn- 
ing fuse  had  seemingly  caused  a  part  of  the  fulminating  composition 
to  detonate,  the  detonation  destroying  the  top  part  of  the  copper 
shell  but  not  being  propagated  throughout  the  remainder  of  the  wet 
fulmmating  charge.  In  these  instances  a  slight  report  only  was 
audible.  Obviously  an  explosion  of  this  order  would  not  cause  a  com- 
plete detonation  of  dynamite  or  other  high  explosives.  In  some  of 
the  tests  a  thin  coating  of  tallow  was  placed  on  the  fuse  one-fourth  of 
an  inch  from  the  end  and  extending  a  distance  of  one-half  of  an  inch 
up  on  the  fuse.  In  the  tests  in  which  tallow  was  placed  around  the 
fuse  before  it  was  inserted  into  the  detonator  a  more  perfect  seal  was 
made. 

A  new  crimper  recently  placed  on  the  market  crimps  the  detonator 
on  the  fuse  in  a  manner  different  from  that  of  any  of  the  other  types 
of  crimpers.  The  salient  feature  of  this  crimper  is  its  ability  to  con- 
tract the  top  of  the  detonator  uniformly  and  to  form  a  J-inch  groove 
around  the  copper  shell,  thus  perfecting  a  seal  of  the  detonator  on  the 
fuse  that  will  permit  submersion  under  water  for  30  minutes.  The 
shell  is  pressed  firmly  and  uniformly  into  the  fuse,  but  not  far  enough 
to  break  or  separate  the  powder  train.  Owing  to  the  varying  diame- 
ters of  different  types  of  fuse  and  the  probability  of  considerable 
variation  in  the  same  type  or  even  in  the  same  coil  of  fuse,  the  use  of  a 
thin  film  of  tallow  around  the  end  of  the  fuse  that  is  inserted  into  the 
detonator,  as  described  above,  will  make  a  better  seal  irrespective 
of  the  crimper  used. 

TESTS  WITH  A  TRINITROTOLUENE  DETONATING  FUSE. 

As  the  results  of  all  tests  made  with  explosives  sensitive  to  deto- 
nation showed  that  when  a  complete  detonation  was  obtained  the  rate 
of  detonation  was  practically  the  same,  the  authors  decided  to  carry 
on  tests  with  a  few  explosives,  using  No.  6  electric  detonators  and 
trinitrotoluene  detonating  fuse  as  the  initiatory  explosive. 

The  trinitrotoluene  detonating  fuse  used  in  the  tests  was  a  lead  tube 
filled  with  trinitrotoluene,  and  is  commercially  known  as  "cordeau 
detonant."  The  results  of  physical  examination  of  the  fuse  were  as 
follows. 


TESTS    WITH    A    TKINITROTOLUENE    DETONATING    FUSE. 


67 


Results  of  physical  examination  of6-mm.  detonating  fuse  (cordeau  detonant). 

Outside  diameter,  inches 0.  2275 

Thickness  of  lead,  inches 0275 

Inside  diameter  of  tube,  inches 1725 

Weight  of  a  foot  length,  grams 41.  74 

Weight  of  a  foot  length  of  lead  tube,  grams 35.  32 

Weight  of  a  foot  length  of  charge,  grams 6.  42 

Density  of  charge 1.  40 

Consistency  of  charge :  Powdered;  very  fine;  dry;  soft;  slightly  cohesive. 
Color  of  charge:  Straw. 

The  tests  were  made  with  explosives  in  which  a  6-inch  length  of 
the  detonating  fuse  (cordeau  detonant)  was  embedded  centrally 
at  one  end  of  the  charge,  the  side  of  the  fuse  being  slit  and  spread 
open  from  one  end  a  distance  of  1J  inches.  A  No.  6  electric  detonator 
was  placed  against  the  trinitrotoluene  in  the  slit  and  tied  firmly  in 
place.  The  electric  detonator  and  attached  detonating  fuse  (cordeau 
detonant)  was  imbedded  in  the  explosive.  Following  is  a  tabulation 
of  the  results  of  the  tests: 

Results  of  rate-of -detonation  tests  of  explosives  with  a  No.  6  electric  detonator  and  detonat- 
ing fuse  (cordeau  detonant). 


Class  of  explosive. 

Test  No. 

Rate  of 
detonation. 

Average 
rate  of 
detonation. 

Class  1,  subclass  a  (sample  1)  

D981 

Meters  per 
second. 
2,231 

Meters  per 
second. 

Class  1,  subclass  b  (sample  2)  

D982 
D990 

2,225 
(a) 

\           2,  228 

\ 

20  per  cent  "straight"  nitroglycerin  dynamite..                              .  . 

D991 
D1007 

Rj 

3,156 

}  

1 

40  per  cent  strength  ammonia  dynamite  (containing  nitrosubsti- 
tution  compounds)                                   

D1008 
D1009 

D880 

2,947 
3,190 

2,  441 

[           3,098 

35  per  cent  strength  gelatin  dynamite  (two  years  old)  

D883 
D884 
D885 
D886 

D893 

(a) 
2,945 
2,821 
2,713 

(a) 

2,731 
\ 

D894 

PI 

}  

a  Incomplete  detonation;  rate  not  determined. 

Comparative  results  of  tests  with  detonating  fuse  fired  with  No.  6  detonators  and  with  No.  6 
electric  detonators  used  alone. 


No.  6 
electric  de- 
tonator and 
detonating 
fuse. 

No.  6 

electric 
detonator. 

Averages  of  the  rate  of  detonation  of  three  explosives  meters  per  second 

2,686 

2,645 

Explosive  efficiency,  Der  cent       

101.6 

100.0 

The  results  of  the  tests  show  that  a  6-inch  length  of  detonating 
fuse  (cordeau  detonant)  used  in  connection  with  a  No.  6  electric 
detonator  does  not  increase  the  rate  of  detonation  of  the  explosives 


68   INVESTIGATIONS  OF  DETONATOKS  AND  ELECTRIC  DETONATOES. 


tested.  The  slight  increase  indicated  in  the  table  is  explained  by  the 
fact  that  the  rate  of  detonation  of  detonating  fuse  (cordeau  detonant) 
itself  is  about  4,900  meters  per  second  and  that  the  fuse  extended 
about  one-eighth  the  length  of  the  charge. 

If  the  detonating  fuse  had  extended  the  full  length  of  the  charge 
the  rate  of  detonation  of  the  explosive  would  probably  have  been 
increased  to  4,900  meters  per  second,  the  rate  of  the  detonating  fuse. 

Detonating  fuse  has  been. used  to  some  extent  in  deep-hole  blasting. 
A  piece  of  the  fuse  is  laid  beside  the  charge  of  high  explosive  that  has 
been  inserted  into  the  hole.  The  fuse,  when  detonated,  accelerates 
the  rate  of  detonation  of  the  explosive,  thus  producing  a  greater  shat- 
tering effect  on  the  surrounding  rock.  Detonating  fuse  has  also  been 
used  to  replace  electric  detonators  in  large  blasts  when  simultaneous 
blasting  is  desired.  Obviously,  when  detonating  fuse  is  used  in  drill 
holes  containing  a  long  charge  of  explosive  whose  rate  of  detonation 
is  less  than  that  of  the  detonating  fuse,  a  greater  shattering  effect  will 
be  produced.  When  the  rate  of  detonation  of  the  explosive  charge  is 
greater  than  that  of  the  detonating  fuse,  the  only  advantage  in  using 
the  fuse  would  be  to  insure  a  complete  detonation  of  the  entire 
charge  of  explosive. 

TESTS   WITH  DETONATORS    DISTRIBUTED   IN   CHARGE. 

With  long  charges  of  high  explosives  in  blasting  work,  it  has  some- 
times been  the  custom  to  place  detonators  at  intervals  in  the  charges, 
in  the  belief  that  the  work  accomplished  by  the  explosives  would  be 
increased.  Rate-of-detonation  tests  were  made  with  an  explosive  of 
class  1,  subclass  a,  sample  3  (an  ammonium-nitrate  explosive  con- 
taining a  sensitizer  that  is  itself  an  explosive),  in  charges  1 J  inches  in 
diameter,  with  and  without  No.  7  detonators  distributed  in  the  explo- 
sive, to  determine  whether  detonation  of  the  charge  would  occur  at 
a  greater  distance  because  of  the  presence  of  the  detonators.  The 
explosive  had  been  previously  tested  (see  p.  29)  in  charges  1J 
inches  in  diameter,  with  the  result  that  the  No.  7  electric  detonator 
caused  complete  detonation  in  every  trial,  whereas  the  No.  3  electric 
detonator  failed  to  do  so  once  out  of  three  trials.  The  explosive  was 
insensitive  to  detonation  and  was  purposely  chosen  for  this  reason. 
The  results  were  as  follows: 
Results  of  rate-of-detonation  tests  in  which  No.  7  detonators  ivere  distributed  in  the  charge* 


Grade  of  detonator. 

Test  No. 

Dimensions  of  galvan- 
ized-iron  tube  used. 

Result. 

Diameter. 

Length. 

No.  7 

o  D1134 

6  D1147 
c  D1148 

Inches. 
IJ 

11 

Inches. 
42 

80 
42 

Detonation  in- 
complete. 
Do. 
Do. 

No.  7 

No.7....".  

«  No  detonators  distributed  in  the  charge. 

b  Three  No.  7  detonators  placed  every  one-half  meter  in  the  charge. 

c  Three  No.  7  detonators  placed  every  one-fourth  meter  in  the  charge. 


TESTS   WITH   DETONATORS   DISTRIBUTED  IN   CHARGE. 


69 


Further  tests  were  made  with  an  insensitive  gelatin  dynamite  by 
placing  one  No.  7  detonator  every  one-eighth  meter  in  the  charge, 
with  results  as  follows : 

Results  of  rate-of -detonation  tests  in  which  No.  7  detonators  were  distributed  in  the  charge. 


Grade  of  detonator. 

Diameter  of 
cartridges. 

Dimensions  of  galvan- 
ized-iron  tube  used. 

Length  of 
charge  that 
detonated. 

Diameter. 

Length. 

No  7                                                                   

Inches. 
14 
li 
li 

Inches. 
If 
if 
li 

Inches. 
42 
42 
42 

Inches. 
211 

16 
20 

No  7 

No  7                                                                 

The  results  of  rate-of-detonation  tests  with  the  same  explosive, 
when  no  extra  detonators  were  used,  were  as  follows: 

Results  of  rate-of -detonation  tests  without  extra  detonators. 


Grade  of  detonator. 

Diameter  of 
cartridge. 

Dimensions  of  galvan- 
ized-iron  tube  used. 

Length  of 
charge  that 
detonated. 

Diameter. 

Length. 

No.  7 

Inches. 

H 
l| 

li 

Inches. 

11 

Inches. 
42 
42 
42 

Inches. 
6 
15 
9 

No.  7... 

No.  7    . 

The  results  of  the  tests  tabulated  above  indicate  that  extra  detona- 
tors distributed  5  inches  apart  in  a  cartridge  file  of  an  insensitive 
explosive  40  inches  long  have  a  slight  tendency  to  increase  the  propa- 
gation of  the  explosive  wave,  but  that  extra  detonators  placed  10 
inches  apart  offer  no  advantage. 

With  an  insensitive  gelatin  dynamite,  such  as  that  used  in  the 
tests,  the  influence  of  the  detonator  probably  does  not  extend  further 
than  5  inches.  Furthermore,  the  explosion  wave  and  the  detonation 
of  the  explosive  surrounding  the  detonator  probably  precede  the 
explosion  of  the  detonator.  Assuming  this  to  be  true,  the  detonator 
is  exploded  in  the  products  of  combustion  of  the  explosive,  and, 
accordingly,  offers  little,  if  any,  advantage  as  a  means  of  extending 
the  explosive  wave. 

Attention  is  called,  however,  to  the  fact  that  it  is  often  advan- 
tageous to  fire  simultaneously  two  or  more  electric  detonators  placed 
in  different  parts  of  the  charge  in  the  same  drill  hole.  Under  these 
conditions,  if  the  charge  is  fired  simultaneously,  the  time  of  detonation 
would  be  reduced,  and,  accordingly,  the  shattering  effect  of  the 
explosion  would  be  materially  increased.  Also  when  long  charges 
of  explosives  are  used,  it  is  sometimes  necessary  to  use  more  than  one 
electric  detonator  in  the  charge  to  insure  complete  detonation. 


70   INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 

In  quarry  operations  the  large  drill-hole  method  of  blasting  is 
being  rapidly  introduced.  The  former  practice  of  quarrying  by  the 
bench  method  and  drilling  holes  of  small  diameter,  which  in  many 
cases  requires  the  chambering  of  the  bottom  of  the  drill  holes  before 
loading  the  main  charge,  is  more  expensive. 

In  some  quarries  6-inch  holes  are  drilled  100  feet  in  depth,  and 
several  thousand  pounds  of  explosive  is  used  in  a  blast.  The  charges 
usually  extend  to  a  distance  of  30  feet  up  from  the  bottom  of  the 
holes.  It  has  been  found  that  when  one  electric  detonator  is  placed 
in  the  top  of  the  charge  it  will  not  always  produce  a  complete  det- 
onation of  the  entire  charge  in  the  drill  hole;  therefore  two  or  more 
electric  detonators  distributed  throughout  the  charge  are  generally 
used.  When  the  most  violent  effect  is  desired  in  blasting,  the  best 
method  of  placing  electric  detonators  in  a  charge  30  feet  in  length, 
irrespective  of  whether  they  are  connected  in  series  or  parallel,  is  to 
place  one  electric  detonator  5  feet  from  the  bottom  of  the  charge, 
one  5  feet  below  the  top  of  the  charge,  and  one  in  the  center  of  the 
charge.  Assuming  that  the  entire  charge  detonates  at  a  uniform 
rate,  if  the  three  electric  detonators  are  fired  simultaneously  it  can 
readily  be  seen  that  the  duration  of  the  explosive  reaction  will  be 
one-sixth  of  the  time  that  would  be  required  if  one  electric  detonator 
were  used  in  the  top  of  the  charge. 

Tests  were  made  at  the  bureau's  Pittsburgh  testing  station  to 
determine  whether  simultaneous  explosion  would  occur  when  four 
of  the  P.  T.  S.  S.  No.  6  electric  detonators  were  connected  in  series 
and  fired  with  different  sources  of  electric  current.  In  the  tests  in 
which  a  4-hole  firing  machine  of  the  dynamo-electric  type  was 
used,  the  time  interval  that  elapsed  between  the  firing  of  the  first 
and  the  last  electric  detonator  of  each  series  varied  from  0.0004  to 
0.0050  second.  As  it  requires  only  0.0020  second  for  30  feet  of  40 
per  cent  'straight"  nitroglycerin  dynamite  to  detonate,  it  is  obvious 
that  in  many  cases  the  only  advantage  in  using  more  than  one 
electric  detonator  in  the  same  charge,  when  fired  with  a  4-hole  firing 
machine,  would  be  to  insure  complete  detonation  of  the  charge.  It 
is  to  be  noted  that  the  time  interval  between  the  firing  of  the  first 
and  the  last  electric  detonator  is  in  some  cases  greater  than  the  time 
required  for  30  feet  of  40  per  cent  dynamite  to  detonate.  When  a 
4-hole  firing  machine  is  used  to  fire  four  electric  detonators  con- 
nected in  series  there  is  not  sufficient  current  generated  to  fuse  the 
platinum  wires  in  the  electric  detonators.  The  wires  are  brought  to 
different  temperatures,  depending  on  their  cross-sectional  area  and, 
accordingly,  the  ignition  of  the  priming  charge  in  the  electric  de- 
tonators is  not  simultaneous,  nor  is  its  burning  or  detonation  uniform. 
These  causes  are  assumed  to  be  responsible  for  the  delay  that  occurs 
in  the  explosion  of  the  electric  detonators. 


USE    OF   TWO    KINDS   OF   EXPLOSIVES   IN    SAME   DRILL   HOLE.       71 

Further  tests  were  made  by  using  a  10-hole  firing  machine,  all 
other  conditions  being  the  same  as  in  the  previous  tests.  The 
machine  furnished  ample  current  to  fuse  the  platinum  wires  in  the 
electric  detonators  and  they  were  therefore  fired  practically  simul- 
taneously. The  time  interval  was  only  0.0001  second.  In  order  to 
obtain  the  benefit  of  simultaneous  blasting  when  two  or  more  electric 
detonators  are  to  be  fired,  the  source  of  electric  current  should  be 
such  as  to  insure  the  instantaneous  fusing  of  all  the  bridges  in  the 
electric  detonators.  This  can  be  best  accomplished  in  practical 
operations  by  wiring  all  electric  detonators  in  parallel  and  using  a 
light  or  power  circuit  for  firing.  If  a  high-pressure  alternating  cur- 
rent is  the  only  source  of  electricity  available,  it  may  be  necessary 
to  install  a  transformer  in  order  to  obtain  the  proper  pressure  with- 
out injury  to  the  leading  wires.  A  lamp  bank  or  a  short  length  of 
fuse  wire  is  sometimes  placed  in  the  electric  circuit  and  answers  the 
same  purpose,  irrespective  of  the  kind  or  the  pressure  of  the  current 
supplied.  However,  if  a  lamp  bank  or  a  fuse  wire  is  used,  it  should 
have  a  greater  current-carrying  capacity  than  is  necessary  to  fire  all 
of  the  electric  detonators. 

USE  OF  TWO  KINDS  OF  EXPLOSIVES  IN  THE  SAME  DRILL 

HOLE. 

In  certain  quarry  operations  in  the  Middle  West,  owing  to  varia- 
tions in  the  hardness  and  structure  of  the  different  strata,  it  is  neces- 
sary to  use  more  than  one  kind  of  explosive  in  the  same  drill  hole. 
The  part  of  the  drill  hole  that  penetrates  the  hardest  stratum  is 
usually  loaded  with  an  explosive  having  a  high  rate  of  detonation. 
The  remainder  of  the  charge  may  be  an  explosive  having  an  inter- 
mediate rate.  In  some  cases  black  blasting  powder  is  used,  provided 
there  are  no  pronounced  clay  seams  or  other  irregularities  that 
would  allow  the  gases  evolved  on  the  explosion  of  the  black  blasting 
powder  to  escape  before  the  main  charge  detonated.  In  work  of 
this  kind,  the  holes  are  drilled  vertically  15  to  20  feet  deep,  and 
there  is  always  sufficient  stemming  used  to  insure  the  maximum 
effect  of  the  blast,  even  when  the  explosives  used  in  the  same  drill 
hole  detonate  at  different  rates. 

The  practice  of  using  combination  charges  of  explosives  has  been 
recently  adopted  in  some  coal  mines.  The  drill  holes  are  usually 
shallow  and,  accordingly,  do  not  permit  the  use  of  sufficient  stem- 
ming properly  to  confine  the  gases  when  they  are  evolved  at  different 
rates.  Under  such  conditions  fires  and  blown-out  shots  are  likely  to 
result. 

Several  tests  made  at  the  Pittsburgh  testing  station  to  determine 
the  energy  developed  by  combination  charges  showed  that  there  was 
no  advantage  in  using  them  under  conditions  that  simulated  blasting 
in  coal.  In  some  of  the  tests,  a  No.  6  detonator  (blasting  cap)  was 


72        INVESTIGATIONS  OF  DETONATORS  AND  ELECTRIC  DETONATORS. 

inserted  in  the  charge  of  dynamite,  and  placed  in  the  back  of  the 
bore  hole.  In  front  of  the  detonator  a  charge  of  black  blasting 
powder,  containing  a  black  powder  igniter,  was  placed,  and  the  free 
part  of  the  drill  hole  was  then  well  tamped  with  clay. 

The  results  of  the  tests  made  in  the  ballistic  pendulum,  using 
combination  charges  of  40  per  cent  "straight"  nitroglycerin  dyna- 
mite and  FFF  black  blasting  powder,  with  and  without  a  No.  6 
detonator  embedded  in  the  explosive,  were  as  follows : 

The  swings  of  the  ballistic  pendulum0  in  those  tests  in  which  the 
detonator  was  used  were  3.42,  3.41,  3.40,  3.41,  3.26,  3.32,  3.01,  3.34, 
and  3.28  inches;  average,  3.32  inches.  In  those  tests  in  which  no 
detonator  was  used  the  swings  were  3.58,  3.30,  3.32,  3.38,  3.24,  3.31, 
3.22,  3.36,  and  3.31  inches;  average,  3.34  inches. 

The  tests  indicated  that  there  is  no  advantage  in  using  an  extra 
detonator  in  the  dynamite,  as  the  explosion  of  the  black  blasting 
powder  is  sufficient  to  cause  complete  detonation.  Many  accidents 
have  occurred  in  coal  mines  where  combination  charges  containing 
detonators  were  used.  When  squibs  are  used  for  firing,  it  is  neces- 
sary to  insert  a  needle  into  the  charge  of  black  blasting  powder,  and 
there  is  always  then  a  possibility  of  the  needle  coming  in  contact 
with  the  detonator. 

The  practice  of  using  combination  charges  in  coal  mines  offers  no 
advantage,  and,  as  there  are  many  dangers  attendant  upon  their  use, 
the  practice  should  be  discouraged. 

PUBLICATIONS     ON    MINE    ACCIDENTS    AND    TESTS    OF 

EXPLOSIVES. 

The  following  Bureau  of  Mines  publications  may  be  obtained  free 
by  applying  to  the  Director  Bureau  of  Mines,  Washington,  D.  C.: 

BULLETIN  10.  The  Use  of  Permissible  Explosives,  by  J.  J.  Rutledge  and  -Clarence 
Hall.  1912.  34  pp.,  5  pis. 

BULLETIN  15.  Investigations  of  Explosives  Used  in  Coal  Mines,  by  Clarence  Hall, 
W.  O.  Snelling,  and  S.  P.  Ho  well,  with  a  chapter  on  the  natural  gas  used  at  Pittsburgh, 
by  G.  A.  Burrell,  and  an  introduction  by  C.  E.  Munroe.  1911.  197  pp.,  7  pis. 

BULLETIN  17.  A  Primer  on  Explosives  for  Coal  Miners,  by  C.  E.  Munroe  and  Clar- 
ence Hall.  61  pp.,  10  pis.  Reprint  of  United  States  Geological  Survey  Bulletin  423. 

BULLETIN  20.  The  Explosibility  of  Coal  Dust,  by  G.  S.  Rice,  with  chapters  by 
J.  C.  W.  Frazer,  Axel  Larsen,  Frank  Haas,  and  Carl  Scholz.  204  pp.,  14  pis.  Reprint 
of  United  States  Geological  Survey  Bulletin  425. 

BULLETIN  44.  First  National  Mine-Safety  Demonstration,  Pittsburgh,  Pa.,  October 
30  and  31,  1911,  by  H.  M.  Wilson  and  A.  H.  Fay,  with  a  chapter  on  the  explosion  at 
the  experimental  mine,  by  G.  S.  Rice.  1912.  75  pp.,  7  pis. 

BULLETIN  46.  An  Investigation  of  Explosion-Proof  Mine  Motors,  by  H.  H.  Clark. 
1912.  44  pp.,  6  pis. 

BULLETIN  48.  The  Selection  of  Explosives  Used  in  Engineering  and  Mining  Opera- 
tions, by  Clarence  Hall  and  S.  P.  Howell.  1913.  50  pp.,  3  pis. 

°  The  ballistic  pendulum  used  by  the  Bureau  of  Mines  is  a  large  mortar  swung  from  a  pivoted  support. 
The  explosive  to  be  tested  is  fired  from  a  small  cannon  into  the  mouth  of  the  mortar,  and  the  swing  of  the 
mortar  is  taken  as  a  measure  of  the  strength  of  the  explosive. 


PUBLICATIONS   ON    TESTS   OF   EXPLOSIVES.  73 

BULLETIN  52.  Ignition  of  Mine  Gases  by  the  Filaments  of  Incandescent  Lamps,  by 
H.  H.  Clark  and  L.  C.  Ilsley.  1913.  31  pp.  6  pis. 

TECHNICAL  PAPER  4.  The  Electrical  Section  of  the  Bureau  of  Mines,  Its  Purpose 
and  Equipment,  by  H.  H.  Clark.  1911.  12  pp. 

TECHNICAL  PAPER  6.  .The  Rate  of  Burning  of  Fuse  as  Influenced  by  Temperature 
and  Pressure,  by  W.  O.  Snelling  and  W.  C.  Cope.  1912.  28  pp. 

TECHNICAL  PAPER  7.  Investigations  of  Fuse  and  Miners'  Squibs,  by  Clarence  Hall 
and  S.  P.  Howell.  1912.  19  pp. 

TECHNICAL  PAPER  11.  The  Use  of  Mice  and  Birds  for  Detecting  Carbon  Monoxide 
After  Mine  Fires  and  Explosions,  by  G.  A.  Burrell.  1912.  15  pp. 

TECHNICAL  PAPER  12.  The  Behavior  of  Nitroglycerin  When  Heated,  by  W.  O, 
Snelling  and  C.  G.  Storm.  1912.  14  pp.,  1  pi. 

TECHNICAL  PAPER  13.  Gas  Analysis  as  an  Aid  in  Fighting  Mine  Fires,  by  G.  A. 
Burrell  and  F.  M.  Seibert.  1912.  16  pp. 

TECHNICAL  PAPER  14.  Apparatus  for  Gas- Analysis  Laboratories  at  Coal  Mines,  by 
G.  A.  Burrell.  1913.  24  pp.,  7  figs. 

TECHNICAL  PAPER  17.  The  Effect  of  Stemming  on  the  Efficiency  of  Explosives,  by 
W.  0.  Snelling  and  Clarence  Hall.  1912.  20  pp. 

TECHNICAL  PAPER  18.  Magazines  and  Thaw  Houses  for  Explosives,  by  Clarence 
Hall  and  S.  P.  Howell.  1912.  34  pp.,  1  pi. 

TECHNICAL  PAPER  19.  The  Factor  of  Safety  in  Mine  Electrical  Installations,  by 
H.  H.  Clark.  1912.  14  pp. 

TECHNICAL  PAPER  21.  The  Prevention  of  Mine  Explosions;  Report  and  Recom- 
mendations, by  Victor  Watteyne,  Carl  Meissner,  and  Arthur  Desborough.  12  pp. 
Reprint  of  United  States  Geological  Survey  Bulletin  369. 

TECHNICAL  PAPER  22.  Electrical  Symbols  for  Mine  Maps,  by  H.  H.  Clark.  1912. 
11  pp.,  8  figs. 

TECHNICAL  PAPER  23.  Ignition  of  Mine  Gas  by  Miniature  Electric  Lamps,  by 
H.  H.  Clark.  1912.  5  pp. 

TECHNICAL  PAPER  24.  Mine  Fires,  a  Preliminary  Study,  by  G.  S.  Rice.  1912. 
51pp. 

TECHNICAL  PAPER  28.  Ignition  of  Mine  Gas  by  Standard  Incandescent  Lamps,  by 
H.  H.  Clark.  1912.  6  pp. 

TECHNICAL  PAPER  40.  Metal-Mine  Accidents  in  the  United  States  during  the  Cal- 
endar Year  1911,  by  A.  H.  Fay.  1913.  54  pp. 

TECHNICAL  PAPER  46.  Quarry  Accidents  in  the  United  States  during  the  Calendar 
Year  1911,  compiled  by  A.  H.  Fay.  1913.  32  pp. 

TECHNICAL  PAPER  48.  Coal-Mine  Accidents  in  the  United  States,  1896-1912,  with 
Monthly  Statistics  for  1912,  by  F.  W.  Horton.  1913.  72  pp. 

TECHNICAL  PAPER  53.  Proposed  Regulations  for  the  Drilling  of  Gas  and  Oil  Wells, 
with  Comment  thereon,  by  0.  P.  Hood  and  A.  G.  Haggem.  1913.  28  pp.,  2  figs. 

MINERS'  CIRCULAR  3.  Coal-Dust  Explosions,  by  G.  S.  Rice.     1911.     22pp. 

MINERS'  CIRCULAR  4.  The  Use  and  Care  of  Mine-Rescue  Breathing  Apparatus,  by 
J.  W.  Paul.  1911.  24  pp. 

MINERS'  CIRCULAR  5.  Electrical  Accidents  in  Mines;  Their  Causes  and  Preven- 
tion, by  H.  H.  Clark,  W.  D.  Roberts,  L.  C.  Ilsley,  and  H.  F.  Randolph.  1911.  10 
pp.,  3  pis. 

MINERS'  CIRCULAR  6.  Permissible  Explosives  Tested  Prior  to  January  1,  1912,  and 
Precautions  to  be  Taken  in  Their  Use,  by  Clarence  Hall.  1912.  20  pp. 

MINERS'  CIRCULAR  9.  Accidents  from  Falls  of  Roof  and  Coal,  by  G.  S.  Rice.  1912. 
16pp. 

MINERS'  CIRCULAR  10.  Mine  Fires  and  How  to  Fight  Them,  by  J.  W.  Paul.  1912. 
14pp. 

MINERS'  CIRCULAR  11.  Accidents  from  Mine  Cars  and  Locomotives,  by  L.  M. 
Jones.  1912.  16  pp. 

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